It is something to think about. There must be a ready made tent out there with a footprint of say 4' X 6+'. Weight is an issue, but with bicycle wheels and tires that leaves the platform itself as the challenge... something as strong as plywood without the weight. If the axle was midway then both ends could have telescoping legs at the corners. Even 3' wide would be enough for an old guy & his dog. Platform could be hinged into thirds to fold in on itself. Wouldn't take long to set up a pup tent on it. Come to think of it I have an extra kiddie trailer frame... hmmm...something to think about for sure.
SB