Can I claim prior to tax year 2024 interest on my RV mortage loan if I had not claimed any prior?

Only by amending past year returns.  You cannot put any past year interest on a 2024 tax return.    The interest is an itemized deduction that goes on Schedule A.   If you do not have enough itemized deductions to exceed your standard deduction, the interest will not change anything.

No not the prior.  Just interest  you paid in 2024.  You would need to amend the prior years to add the interest you paid for that year.  

No, you can't claim prior-year mortgage interest on your current year tax return, but you can amend your prior-year tax return.

For more information and instructions to amend your prior year return, review the TurboTax articles  How to Correct Federal Tax Returns, How to File an Amended Tax Return with the IRS and  Video: How to Amend Your Tax Return.