This has been covered above to some degree, but the older Airstream trailers used face frame construction for cabinetry where the 'face' of the cabinet is 3/4" wood but the sides are 1/4" plywood. If you pay attention to fitting the panels to the frame and attaching the sides to the walls of the trailer, you get a simple, but strong, type of structure. The aluminum extrusions allow flexing, but they also can be used to distribute the load of an overhead cabinet when you want to hang the cabinet to the wall and ceiling. You can attach cabinet walls to the trailer walls with corner brackets but keep in mind that 1/4" plywood is flexible and that the aluminum extrusions coupled with good attachment to a face frame make for a pretty strong and firm wall. Just my $0.02 worth.
1966 Airstream Caravel
2006 Toyota Tacoma