NOT encouraging debt but if you are going to use debt and a lender accepts RV as collaterol, the RV will qualify as a second home by IRS: requires sleeping, cooking, and toilet facilities AND debt secured by RV.
NOTE: Always do your own tax research but points you directly to IRS pub
IRS Publication 936
clickyQualified Home
For you to take a home mortgage interest deduction, your debt must be secured by a qualified home. This means your main home or your second home. A home includes a house, condominium, cooperative, mobile home, house trailer, boat, or similar property that has sleeping, cooking, and toilet facilities.