This little space can definitely be transformed into a guest bed/office. The trundle sounds perfect, either that or a pull out sofa would work well. Under the window would be a great spot for this. It's sets it out of the way as much as possible. The desk should sit on the opposite wall where the TV is. Maybe position the TV on the wall that you face when you first walk in- the green accent wall. Pull from the rest of your house a color that you like. Keep it very light, like a light blue, light grey, etc. Since it's a small space keeping things light is key. What about an accent wallpaper?

A great way to cover carpet is with a large area rug. YES a rug can go on carpet, I love using them for this purpose. It also helps to anchor a space. Keep a very low pile or kilim type rug that is very thin. Check out these small guest room/offices for inspo. Good luck!

It would help to give dimensions. I think a daybed with trundle or a Murphy bed would work best. I think it would be better centered on the back wall. Put 2 night tables on each side of it. Get a small desk with cubbies that will fit on the wall between the door and the window and put the tv on top of it. It will be directly across from the bed and higher so it would be better tv viewing. It is a small room. Is there a closet? A guest room doesn't really need one. So your desk could also be tucked into a closet with doors open to use when you don't have guests and just close the doors when you do. Your work is easily hidden. Have fun

Somethings to consider regarding a trundle bed. Since the trundle part is basically on the floor, will this be an issue for one of them to get up and down from. The one that sleeps in the bed if the trundle is out, will it be a problem for them to get out of the bed as more than likely they will have to walk on the trundle mattress which could be a problem if they have to make a night trip to the bathroom. Also, it appears that if you put a trundle bed and a desk in this room that if you pull out the trundle there may not be any room for the desk. IMO- if a desk will be used more than the bed then you might consider just getting a blow up mattress for when your parents visit. As you can always give them your bed if it fits two people and you take the blow up mattress.

If you still want a bed in there, the best thing to do is find one you like, take the measurements and then blue tape it out on the carpet- include the trundle pulled out and then you can figure out where it works the best and if you have room for a desk.

Some trundles store under the bed when not in use but lift up to the bed height to basically make a king bed search on shop. there are lots of different styles. But I guess only you can decide what is most important a convenient office or does a guest room make more sense? One takes the back seat

Not a Pro.

Maybe a convertible sofa for an office.

Inspiration:

Montain Home · More Info

I can't tell how big the wall between door and window might be. My first instinct was to put the bed on the window wall and the desk on the wall where the TV is now. I might skip a TV, as it's not really needed by office-worker or occasional visitor, and designing around it becomes a constraint...

Being one of ‘those parents’ and having to sleep in a sometimes guest room...let me tell you that unless your folks are no older than 50,
trundles are so difficult. The upper person has to crawl over the trundle. The lower person can no longer get up from the low mattress “ Help!
I have fallen and can’t get up !!”
In addition, pull out sofas are notorious for having a giant hole in the center of the mattress.
Murphy beds are the most comfortable. However the raised air mattresses are OK. I suggest you and hubby take the air mattress and sacrifice your bed for a few days. Oh! My aching back!!

Almost forgot...friends have pretty white bunk beds..single on top and double below.
May work here on the ‘green’ Wall.

Hi Nicole. Few questions

1. Dimensions of the room? Especially the width of the mint green wall.

2. Are you taking these photos from the bedroom doorway?

3. Is the closet to the immediate right? Is it a double door closet or a single door?

4. What type of office work will you be using the space for? Is this a week at home scenario or do you simply need s desk to pay bills from?

5. What is your planned budget for the redo?

We have a Murphy bed in our small study because it is our overflow/second guest bedroom. Check out Breda Beds. It was a bear to put together and with our desk and file cabinets and shelving for our small business, we managed to get a lot of functionality in one room and it is a great office most of the time.

The trundle will be a problem for older folks. There are sleeper sofas out there with adjustable firmness (using air) that are very comfortable. A queen size futon might be a choice also.

• Adam Tavolo Queen Wall Bed with Desk
• Edge 107" set
• Lumina Queen Wall Bed with Desk
• LGM Queen Transforming Wall Bed

Agree with all that say the trundle will be a problem for older folks.

Try a sleeper sofa. That will give you the most floor space except for when the parents are visiting. You need to try sleeping in there for several days to see what your guests will be experiencing. You can put small tables on each side of the sofa to be used as bedside tables.

Does it also have to be an office? How often will it be used as an office? What furniture do you HAVE to have and what would you like for your office? How will this impact guests and their privacy? Their ability to move around?? Their ability to store their suitcases and ancillary items that need to go somewhere.

There are wall beds with built in desks that simply fold away when the bed is pulled down.

Spazio T Full Size Wall Bed With Table, White · More Info

You might want to explore convertible/sleeper chairs. There are all types of styles. Also, maybe a wall hinged desk where you could drop it down when you need the space for a bed.

Here is a convertiable chair that wouldn't over bear the room. Pretty good reviews, too from Wayfair.

Corrigan Studio Bolen Convertible Chair & Reviews | Wayfair · More Info

Corrigan Studio Bolen Convertible Chair & Reviews | Wayfair · More Info

Some ideas for the desk

hinge desk - Google Search · More Info

hinge desk - Google Search · More Info

hinge desk - Google Search · More Info

following...

Great ideas here! Another idea is using Japanese futon beds. They are rolled up and put away when not in use and allow a clear open floor during the day. The mattresses are not very heavy and might be easier to maneuver than convertible furniture.

consider lighting and reflections when placing office furniture. Perhaps a lightweight desk or a rolling desk that can easily be moved for sleeping?