Folks have been asking for build plans, wiring plans, plumbing details, stud information, construction details on these forums before I ever knew RV.net existed and no one has ever been able to break through the manufacturers deep hidden secrets. Keeping gold at Fort Knox is easier to access than the building diagrams and schematics from an RV manufacturer.
As stated above, your best option is to simply narrow down the camper you are interested in and then out with a tape measure. See if it's do-able. That is probably the only way to get the information.