What I have done, that usually works well, is to email the seller before paying, and don't pay 'till I hear from them. I ask if what Ebay stated was their preferred payment method was true. if they would like a check/ money order, and their mailing address. This even if I plan on using online payment. I then have more contact info. I always click the "ask seller a question" link, as that automatically puts the ebay subject and item number in the subject line.
This doesn't help if you are the seller, like Rog, but I think more of us buy on ebay than sell.
Rog, if you still want to use Ebay (if you are feeling masochistic) you can wait a week or so to relist it, with different pictures, and state that you must pre-approve bidders before allowing them to bid on your item. This will sort out the casual "drive by" bidders, and you can get a little more info from these people.
If I had an extra 3 grand, I would buy your trailer, I could then breed them.

I wonder if there is a market for a brand new 1974 23 foot Argosy?...
Terry