Eric -
My welcome also.
I am presently doing something very similar. I carry my Yamaha TW 200 on a 4 x 8 trailer that I had rigged with a teardrop shaped clamshell frame with a canvas bikini top:

I carry camping supplies in watertight truck boxes:

The rear boxes swing up to unload the TW and also serve as a galley:

Depending on the weather a tent/bed platform (stowed at lower left) attaches to the outside of the trailer with the TW onboard or across the side rails of the trailer with the TW unloaded.
I am now building a fully enclosed slide in unit. There will be removable storage cabinets along the lower inside walls with the rearmost containing a swing out galley. The cabinet tops will support a fold-down bed platform when the TW is unloaded.
Sidewall construction is 5/8 plywood laminated with FRP; roof spars are 3/4 EMT; roof will be FRP floated over Thermo-Ply; windows salvaged from a pick-up cap. No insulation but I may add a couple of vent fans on the upper rear sidewalls. This unit will be primarily for winter and rainy weather, I will continue to use the open teardrop otherwise.


The self locking chock (partially disassembled here) is from Harbor Freight
http://www.harborfreight.com/1800-lb-capacity-motorcycle-standwheel-chock-61670.html but I also use ratchet tie-downs. The small wood blocks center the rear tire but will switch to full length rails to guide the TW when loading since this roof is lower than the teardrop.
The sidewalls are attached to a cedar "shoe" rail to prevent damage to the plywood and FRP when sliding in or out. It can be moved manually or on pvc pipe rollers but I may add casters just for convenience. Finished weight of the slide-in shell will be under 200#. The empty cabinets are 5mm plywood with 2x2 framing and weigh about 30# each empty.
I have not decided on the rear door(s) yet. One option is a fold down ramp but that will inconvenience access to the swing out galley cabinets. Will probably go with a pair of full height barn doors plus a swing up top cover/hatch to provide weather protection using the galley and entering/exiting the camper in bed mode. In either case will be detachable from the shell with hinge pins for ease of sliding in/out.
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