You don’t have to have a designated liveaboard loan in order to take the deduction.
You should find a lender that does liveaboard and submit to them. No point wasting your time with a lender that doesn’t do these loans.
Lenders also have different tiers of rates and requirements depending on the amount of the loan and the age of the boat.
If you have the time it might be a good idea to go to a boat show and visit all the finance booths.