Thing is Gord, you know you're a serious buyer, but how does the seller know that? Best way to show them in my opinion is to call them and have a chat. You can ask questions and hear the answers directly - if the seller pauses or fluffs around over the answers it gives you another level of insight over and above the pictures. If you and the seller build up a rapport on the phone it can help you get prioritised over other prospective buyers.
This happened to me when I bought my current boat from Jersey. Phone calls and a video call tour of the boat led to a sea trial, all because we had built up a rapport on the phone. He held the boat until I could get on a plane to see it in person, despite him having (text-only) interest from local buyers, and the fact that he and I had spoken several times meant he could see that I was genuine which helped him to feel comfortable about letting me have first refusal.
On the flip side, if you call and they don't pick up or don't respond to your answerphone message, isn't that rather a good indication of whether they're serious about selling?