There is always a tax appeal process. This may not get you anywhere initially but hang in there. If denied at the appraiser level, there is usually a local governing board, sometimes called the "Board of Review". At that level, you usually need an attorney to present the case. Not because it is difficult, it is just their rules. If the Board of Review denies you, there is usually a State level Board of Review.
This all sounds pretty intimidating but it mostly consists of submitting paperwork, pictures with dates (if applicable) and some testimony or affidavit to back your case. Some locations like to run it like a court where you show up for the presentations, others it is just a matter of filing the packet. Most locations are moving toward online submissions, so you don't even need to leave your living room.
Local communities, counties and other taxing bodies are cash strapped, so the taxing bodies tell their employees to deny, deny, deny appeals but in a lot of cases, they are violating the law. Don't assume that they know the law or care. Their goal is to hang onto as much money
as they can, so read up on what your rights are and what the law actually says. At the higher review levels, this is where an attorney can help you since he can cite case law and the statutes to make your case.
It also helps if you know what they are charging
others with similar properties (boats). If you are being assessed at a higher level than they are or with a different method of assessment, you have a valid claims. The Freedom of Information Act allows for requests of their documents.
While most of the time, you can look up other properties online, it is a slow process to do it one at a time. If you can FOIA the entire County database, you or a friend with some database skills, can easily pick out similar properties and see how each is taxed. This is easier for real estate where you can boil it down to dollars per square foot by Township but I think this gives you an idea of the process. You'd be surprised at the range of assessments for properties in the same area and with similar characteristics. They get away with what they can.
On the other hand, federal documentation
in another state with a mail drop may be easier. It depends on how your State enforces their property tax laws.