IMO a weird idea who wants to walk out of the main house to go to bed . IMO leave it as a guest space and add on or redo the main house to get what you want.

I would need to see a lot more pictures and a scaled drawing to begin visualizing this.

I grew up in a rambling ranch with a 40' gallery going from the main area of the house to my parents bedroom. The gallery had clearstory windows above closets that had invisible doors (press on the wall panel and it opened into a closet) on one side and pictures lining the wall on the other side. Toward the entrance of the master area the closets stopped and there was a 10' tall, built in triple stack of drawers with a counter on top where my mother displayed several sculptures.

It was dramatic, but my mom complained about the long walk every time she needed to go to her bedroom.

As kids we had fun playing in the gallery - great place to throw superballs or roller skate or run while being chased by a sibling. (Bed was centered in the master so you could run completely around the bed and back out the door.)

I did look at a home when I was house shopping that also had a long hallway between the living area and the master (probably 20'). In the center of the hallway they had a set of French Doors leading out to the outdoor kitchen seating area. It was very nicely done.