"Not a candidate for buying....."
Hmmmm. that's a new one, but I can understand the sellers point. Why wait for a "Maybe" buyer to come from out of town to look & haggle, when there are 5 buyers waiting in line waving Ben Franklins in the air.
When I bought two of my 13' eggs (a Scamp
and a Bigfoot) I replied to ads within and hour after they appeared and fortunately, as were both were within 75 miles and I was able to look at & purchased the trailers on the same day. In both cases they had a list of back-up buyers in hand by the time I arrived to look. In another sale I drove all the way to Phoenix, AZ to buy a Scamp on the first day of the ad, with a promise from the seller to hold it until I arrived in about 6 hours, only to have it sold out from under me when I was but 15 minutes from the sellers house.
When I found my Hunter it was 500 miles away, and, as the seller had a real attachment for his trailer, he wanted a "Qualified" buyer, who had the ability to take care of and restore his Baby. After qualifying with my RV resume (LOL) I sent him a $300 deposit and picked it up a week later, sight unseen. All went well.
You are looking for a very narrow selection in the field of FGRV's, limited by make, model size and year range. May I suggest that you open your initial requirements and get into one you can find and live with that until you find that perfect FGRV. As you can tell, selling whatever you buy now will be a cinch to resell when that next one comes along.
To answer your questions:
If I had a buyer that had to travel some distance I would insist on a deposit to hold for a few days at the most, with a no-refund clause if they were a no-show.
Waiting a few days would also give me an opportunity to construct a waiting-to-buy list as well.
At least in California, making a deposit, and receiving a receipt for same, makes you a lien holder and gives you substantial legal recourse should the seller sell it to another buyer. You can actually attack the validity of the new owners title
And, RV dealers usually don't handle FGRV's, especially any RV's over 10 years old, except on consignment.