Another concern with that engine is that the oil pump seal will groove the end of the crankshaft causing an oil leak. The only fix is pulling the powerhead and replacing the oil pump/seal and installing a speedie sleeve on the crank. No big deal if you are mechanically inclined but a couple of...
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A marine boat surveyor inspecting the boat is your best bet for not making an expensive mistake missing something. Personally I would never buy a boat without one.
Take a good look at the 2820 especially if you take more than a few people on the boat. The upgraded deck space is night and day. Think about a bait tank on the deck along with a decent size ice chest and 4 people trying to get around all that stuff and each other. I have no trouble trailering...
If its 5200 hit it with Debond and give the stuff some time to work. The pedestal will just pop off.....hit it with more debond to clean the rest of the sealant off.
Have you considered something like Pro Pedestals. I have them but I haven't installed them yet......I hear they are the shit. Maybe you are over complicating it with tabs, weight shifting, etc.
https://www.gotshockmitigation.com/
I would think a locking gas cap wouldn't make it one season. As soon as saltwater got into lock mechanism and did its thing either jamming it up or corroding it to a solid mass you would be done.
Dont forget any hoses, pumps, etc that could have some leftovers especially if given a chance to solidify. My tank has the same issue and when I get a chance I will probably replace everything as I bought the boat used and I just cant shake that odor no matter how slight.