I will post some pics of my laundry setup with a side shutoff valve in the right side wall. Give me a minute to find them.

this shows the setup with the drain and the shutoff near the back of the right side wall. the opening in the wall is actually the shower connections that service the shower on the other side of the wall:

my cabinets hide the shower opening, that I had done incase of emergency repair. The cabinet would be easier to remove than the shower tile! this is my shelf setup with a false back:

here are more pics:

this square is the outlet I had installed:

the cabinet next to the dryer is the area that the false back is located:

Be sure to install outlet and LED lighting. The false back is behind the detergent bottles on the lower shelf:

You could move your outlet forward probably instead of how I have mine near the back, but you would have to sacrifice one shelf so you could get the drain pipe threaded to the drain that is usually integrated into the shutoff valve. That is my guess anyway.

"Is it difficult to have the shut off valves located next to the washer instead of behind?"

Not difficult.

Other thoughts?

Consider including a flood pan under the stacked set with proper water containment and drainage detailing.

Look at automatic shutoff valves. Watts, Floodstop, or something similar, there are a few out there. If a water sensor on the floor detects moisture, it'll shut off the water supply and sound an alarm.

Your setup is very cool, @enduring...and the cabinets are very handsome! Were they made by someone locally or by a well-known cabinet company?

I live in a high rise and any kind of flood is catastrophically expensive because it floods all the units below.

My washer/dryer (as well as all "wet" appliances - e.g. dishwasher and ice maker for refrigerator) all have flood pans as well as automatic water alarms that shut off the water automatically as soon as a sensor finds water outside of where it belongs. My Bosch washer also has double hoses that are extra sturdy.

In my opinion, this is much better than shutting off valves every time you use the machines. You might forget at some point and it seems quite inconvenient as well. My sinks and toilets have angle stop valves which turn off because those typically have since faucets are changed or toilets can theoretically overflow.

My water situation is a bit unique because the units were not built with the ability to turn off water ONLY to a unit so if a homeowner needs work to be done in their unit all water is shut off to for everyone in the building. The homeowner is charged $2000 for the turn off and everyone is inconvenienced especially in the summer since our central HVAC air conditioner units are linked to central water supply. I installed a "master" turn off valve when I remodeled which means that I have the ability to turn off all water to my unit without involving the building. I also have the basic angle stops for the sinks and toilets.

Sammy, my cabinets made locally in Central Iowa