First, I urge that any buyer inspect the boat and have a sea trial before final payment. Second, unless you have a lot of experience surveying or building boats--hire a professional surveyor. In many cases it will pay to have a mechanic do an inspection of the engine. For example, excessive end play in the crank shaft (flywheel is loose up and down) means that there is not a proper thrust bearing certain year Honda 150's. Checking the thermostat visually will give some idea of the cooling system in general.
Now as to the procedure. First a offer is made with 10% down payment, subject to survey, engine check and sea trail, If all of this goes well, then the final payment is either done in cash, wire transfer or cashier's check. The Cashier's check is the riskiest of the 3. But, one can have the seller's bank confirm that the cashiers check is valid. (When I bought the current 25, the seller wanted a cashier's check. I usually do wire transfers.). In this case I had the private line of the manager of my bank so that his bank could confirm the validity of the cashier's check. After confirmed or wire transfer effected, then the title is signed over.
If the person who is buying is not present, they it may be best practice to have an intermediary (Escrow agent or Attorney) handle the funds transfer. The seller will have sent a scan of his title, and then signs it off, along with a bill of sale--one can even do FaceTime or Zoom, to assure this s done. The title and bill of sale (equally as important) is then sent by a secure mail service. (Such as Fed Ex overnight, with tracking). Your agent at the place where the boat is located, can affirm that the title and bill of sale are in order. (Some states tax the engine and trailer separately from the boat. The three items can be addressed in the bill of sale.
I bought one boat where the seller was just wanted hs loan paid off. I had accounts at that national bank. We arranged for the title to be released to me when I paid off his loan. This took some preliminary planning.
You want your insurance to cover the boat the instant you sign the contract. I make arrangements for that before I leave home. Also if a 3rd party is trailering or flat bedding out the boat--then you need to let your insurance company know who the hauler is, and have your boat covered by the transport. Try and get agreed value on the boat in insurance coverage, plus liability.
There then comes the issue of transport to your home state. Go to You Ship, or one of the agencies. Get the best bid. Be sure that the hauler, has insurance, bonded, and will call you each evening to know what the progress of his hauling is.