Being one that did have to wait for their baby to grow, and had to ride other horses sparingly, I think that buying this horse for ground work and the like is not a bad idea, as long as you have another horse to ride in the meantime.
However, I would not jump this mare in her career. Holy long pasterns.
Our paint, when we bought him as a yearling, he had extremely long pasterns, but now he has grown into them, and they seem fine. Even if the jumping didn't work out, I would most likely train her for dressage, or maybe a hunter, and sell her. Who knows. I will probably be out to see her later this week.
About the trailering thing, we would bring the trailer regardless since I have family health problems, which limits the time we really have to make a 3+ hour trip. It would be with a small 2 horse bumper pull anyway, so not a big deal to haul there and back, empty.