Our local tax office will title boats purchased within the state of Texas. Out of state purchases must go through TPW. The dealer should have known that you can't put two vehicles on one Bill of Sale, but a Bill of Sale carries no weight in Texas. Can't believe they couldn't give you a price for it. Did they give you a Certificate of Origin for the trailer? They should have. Did you get a title for the trailer? The tax rate for boats and trailers are 6.25%, so it really doesn't matter how they split it up. All trailers with a GVW over 4500 pounds require a title (as well as brakes). The 5 year renewal is fairly recent and I don't do it.
I don't know if Florida is a title state for boats or not. I bought a sailboat from there and they didn't have a Florida title, but I don't know if that applies to power boats, or if it depends on length, weight, private vs commercial use, etc.
I've purchased two boats from out-of-state this year--and it's only March! Guess I need mental help...
I've owned 4 power boats, 3 sailboats, and 32 PWCs, and 15 trailers (I think) so I've spent more time at the TPD / tax office than the average person will in a lifetime. Some of the crap I've dealt with! I even had to get our State Senator involved with one boat deal.
On my last boat/trailer purchase, the girl had reached my breaking point. She wanted the odometer reading for the trailer! I said, loud enough for the entire place to hear, "It doesn't HAVE an odometer, it's a BOAT TRAILER!" She had to verify that with her boss. Sometimes it's easier to come back the next day and get another clerk.