I have a paint that I go back and forth with (dressage/western) all the time. I would say to stick to a western type saddle (a lightweight endurance saddle would be a great idea!) for trail riding if you're going for a long distance especially by yourself. The only time I've ever been dumped by my horse was when I was trail riding in my dressage saddle and he flew sideways (in my experience, my dressage saddle wants to slide more than the western, because my horse has no withers) sending me and my saddle over. You might really like to use a synthetic saddle (low maint, too!) for long distance rides, and your horse will, too! Though I will advise not to get a tree-less saddle, because they don't provide enough support for the horse, no matter how nice for the rider.