Thanks
I plan on using aluminum square tube for the framing. The walls will be skinned with aluminum on the outside, then a layer of foam. On the inside the materials vary from hardwood ply to sheet metal. I will probably use VHB tape and construction adhesive wherever visible to avoid lots of fastener holes.
I will use guides at the corners to keep the halves in line, and front and rear linear actuators coordinated by a microcontroller to do the actual task of raising and lowering.
There will probably be some sort of stiff brush material or a rubber gasket in the gap between halves to keep nature out. I need to do some more research on that.
I plan to use this for spring and summer camping only, and keep it garaged in the winter.