Thanks. I didn't think about that.
The other aspect I researched is the issue of Reg Z's 226.35(b)(3)requirement for esscrows. This section includes structures that are classified as personal property under state law as principal dwellings that would require escrow accounts to be established. Therefore, an escrow account would have to be established on a higher priced mortgage loan secured by a first lien on a mobile home, boat or trailer (RV) used as the consumer's principal dwelling.
So it's not prohibited under Reg Z, but it does require the establishment of the escrow if it's higher priced (and usually is for an RV loan). The other institution probably didn't want to mess with the escrow part because it's hard to determine the taxes for a year on something that isn't real estate... In an article I read, it stated several of the larger banks are refusing to make these types of loans because of the escrowing requirement - an unintended consequence of the way Reg Z was written.