The RV fits the definition of dwelling in this case. If it is to be the borrower's principal dwelling, and the APR over APOR spread exceeds one of the three thresholds in 1026.35(a)(1), it will be an HPML, and will be subject to the HPML escrow requirements unless you, as the lender, are exempt from those requirements. You'd have to escrow for insurance and any periodic taxes imposed on the RV (personal property taxes included).
Otherwise, I agree with Ski's analysis.
John S. Burnett
Fighting for Compliance since 1976
Bankers' Threads User #8