I bedlined my 91 Trooper's exterior, and one of my neighbors bedlined his 96 XJ.... actually a lot of guys have bedliner-coated 4x4's.
Nothing to do with aero though (heh... gen 1 isuzu trooper, 33" mud tires a foot wide almost entirely exposed to air flow, solid axles hanging below a very anti-aero belly... not a lot you can do there)
- but damn bedliner makes a tough, simple to repair when scratched or dented, finish.