Only thing I've seen (as far as an all-in-one catalog) are the catalogs aimed at the contractor/skilled trades crowd.
Majority of the content in those catalogs is heavy-duty overhead racks and steel interior divider walls and shelves --- stuff meant for organizing/carrying the tools and heavy parts for plumbers, electricians etc....expensive as heck and not very practically tailored for anyone doing a camper build out. And nothing in those catalogs addresses drivetrain, suspension, exterior lighting, bumpers, etc.....
What you're describing would be great --- haven't come across anything like that yet!
'95 Ford E250 RB30 PH