I was thinking after I typed that last post that maybe down the road if you felt you needed more room, a enclosed car trailer, insulated and carpeted with a A/C unit on the roof might make a nice companion stealth wagon. the way contractors all pull trailers now, nobody would notice.
You could put a comfy couch and big TV in it, with a zip up screen on the ramp door. Then you could have bicycles and other things that you and your son could play with or explore the country with. Maybe even a cheap old golf kart or scooter to run to the corner store with. The front could have a workbench and space for all your tools, thus eliminating the need for the garage.
Think about all that additional roof space for solar panels when the come down in price again.
That way we could follow another one of your very well documented builds!