It looks like you'll need to use wheelchair hubs. If so, you could rig it up to accept quick-release wheelchair wheels. Then you can mark groundability off of your list, since the trailer hitch arm won't need to be removed for it to do so.

Alternately, you could use some kind of system of retractable legs so that you can sleep in it as is, without having to lower it.

That's something like a hundred to a hundred fifty pounds already, just counting the wood parts.

That said, it's a pretty cool project.