You probably are doing this already, but I always started and ended dressage sessions with my horses working on a long rein to let them stretch and relax. It can carry over to the trail. You can also take some contact on your conditioning rides and then give the longer rein where your horse is less likely to charge off - on steep climbs, for instance. Usually, they learn to like the break from dressage contact and learn to know when you will take up the reins and when they can travel along on a long rein.
In my dressage days, the horses got three days in the ring and two days on trail each week. I thought it was really helpful in keeping them (and me) sane.
