Glad this is ending well.
Here's my two cents, as a blundering type who is typically overconfident in his own expertise:
MAKE THE FINE PRINT BIGGER!
(And this goes for everything and everyone, not just people manufacturing fiberglass car bodies for sale).
When I bought my lift, the company had a small note online saying they would ship to a drop point and required the customer to get it home from there. For a person (Alan Merklin, say) who is well-versed in shipping big things, that's probably enough information to trigger some sort of subroutine. For me it meant no small anxiety and many cold-calls/drop-ins at places that operated big flatbeds with forklifts hanging off the back. I was fortunate in this one instance to have had the foresight to arrange all this before swiping my card; I think it took me about a month to get those "last mile" ducks in a row. Many other times in similar situations I've just said "we'll sort it out" and blithely proceeded to heartburn city.
We don't know what we don't know. And while money is the great fixer in all things, it's not always available in sufficient quantities to solve these kinds of problems.
So I think it would be excellent, and save a lot of agita on both sides of the transaction, if the seller of the big item would sort of tap the enthusiastic dummkopf customer on the shoulder and say, "hey, wait: you're sure you've got this shipping thing down? You've done this before? You know it can be a Whole Thing?" And then offer a few suggestions and maybe a step-by-step plan. This shipping primer could fit on a sheet of paper under the headline "READ THIS IF YOU HAVE NEVER SHIPPED SOMETHING BIG AND RIDICULOUS BEFORE."
I doubt you'd lose even a single sale.