I think that's the best starting point. Selling it whole would be the cleanest exit, and it sounds like financially you could ultimately go very low on the price. I just wouldn't start out too low or you signal that the boat is junk. I think Charlie's numbers are a good starting point.
In parallel you could advertise the motors for sale and see what you get. But I expect they will be harder to sell than the whole boat. Plus they will need to be removed, transported, etc., and you will then have a hull that you will have to pay to scrap.
You might also start to investigate the coast to scrap it. I don't know if there are companies that will do that, or if you need to hire an excavator to crush it up and a bunch of dumpsters to haul it away.
I think this is the unfortunately reality of boats as they age out. They will never be worth more than the money that needs to go into them, so they effectively have zero value. I think as you work through this you need to seriously consider just scrapping it right away to cap your losses, possibly holding out the engines for separate sale. You would separate them out anyway because you can get paid for scrap metal, vs having to pay to get rid of fiberglass and wood. And removing the engines will be easy as part of breaking down the boat. Just rip off the top sides, hook a chain to it, and pull it out.