Your photo does not show how much room you have on the "front" side of your entrance, you may have enough.....but you have plenty inside for this:
Why not put the removable section on legs like the rest of the layout, with casters on the legs? You can then roll it in or out depending upon you space.
It should be no problem to secure it to the layout when in place, unhook it and roll it when entering or leaving, and wires can be looped so you have room to move.
You could make it as wide as you wanted to, though you would have to watch for loose scenery items that may fall if moved much. I am sure you could figure out how to solve any problems using this method. I may use it this fall when I put up my Christmas garden, now that I have seen your plan. I like the "around the room" layout, just never put one in the shop over the holiday.
Greg
