I am a recovering rule #1 breaker too. Don't forget to:
give the trailer a hard look. if it's got brakes, figure out a way to check that they actually work. If it is a surge brake style, then when you backup does it have a lockout pin and does it work or do they bind up in reverse? Look at the spring shackles that they are tight and no missing bolts/nuts. That the wiring is not all hillbillyed up. Does it have a tongue jack and if so is it straight and works. Are all the lug nuts on and the same size? Do the trailer axles or any of the frame cross members show any signs of major road hits or encounters with stationary objects?
On the boat - how much gear comes with it? Anchor, safety horn/flotation chit all the stuff that will nickel and dime ya to death after you bring it home.
And good call on the bow wear. It's not bad to have beach marks on it, but if it gets down to the cloth then water can wick it's way into the most amazing places.
Crawl under the dash and check how sano the wiring is or is not. Same dealio back in the engine area. How many generations of cut and splice?
Play devils advocate. Pretend you are rain water and you landed on this boat when it wasn't tarped well or not at all. Where would you run to? Look there for signs of mold, dryrot, silverfish, pill bugs, or basic skank.
And $7500 is in George W Bush dollars, not failed economy dollars.