Pop-up campers, often referred to as tent trailers or tent campers, are lightweight and economical towed devices. The pop-up camper comprises a rigid "base box" lower section and a soft-sided upper section. They are customarily towed flat, in their retracted configuration, then deployed into an enclosed residential space by means of a manual or automated crank, which actuates spring-loaded devices in each corner. Pop-up campers have frames that can be converted into hard-side structures. This involves the removal and replacement of the soft sides, either with hinged panels -- so the top can still be cranked up and down -- or with solid panels.
Extend the pop-up top. Remove the interior except for the fittings you wish to reuse. Retain nothing but the shell, or retain the bunks and bench seats down the sides or amenities such as the furnace, stove, sink and/or the galley.
Make an enclosed trailer with solid sides and a roof for safer hauling or more secure storage, or make a free-standing structure for use in a static location such as a storage shed, chicken house or kennel, or as a retreat for camping, hunting and fishing.
Convert your pop-up camper by retaining the framing and replacing the soft-side material with solid panels braced inside by support ribs. Trade off the weight of the new panels against strength according to the purpose they must serve. Erect lumber ribs, then exclude the elements by panelling the exterior with sheet metal, fibre-reinforced panelling -- colloquially called FRP -- or sheet fibreglass. For theft deterrence, or to maintain a constant temperature, use heavier materials such as plywood.
Prevent drafts and the loss of heated or cooled air by insulating the interior with sheet insulation available from any home improvement warehouse. Use spray glue or contact adhesive to hold the sheets in place. Insulate the corners with external ribs, then use canisters of expanding foam inside.
Use a permanent marker pen to number both the panels and their respective locations if you wish to disassemble and reassemble the structure. You can then reinstall the panels as desired. So long as each individual panel is cut to a size, which allows its storage flat on the floor inside the converted pop-up camper, the collapsed trailer can still be towed in the lowered position. This preserves both towing convenience and the fuel economy of reduced wind resistance.
Pop-up campers are almost universally manufactured with flat roofs. If exposure to the elements -- most particularly snow -- is likely to make this a problem, create a peak with additional panels. Insulate the space to further improve insulation. For residence, plan to include some method of venting air from inside to reduce moisture from cooking, washing and breathing in such a small space.
The spring-loaded actuating devices in the four corners are under considerable pressure, even when relaxed. Be extremely cautious if you remove them. They release with sufficient explosive force to fly out of their locations and can cause serious injury. Do not use improperly vented equipment for cooking or to heat the converted camper interior. Burning propane or waste-oil creates fumes that asphyxiate and become toxic if reburned.