That's what I'm afraid my boy will do at his first ride: turn into a raging Arabian show horse running around, ears perked, nose flared, breathing like he's just run a horse marathon. :) Had Dory been trailered out before to shows or trails? I'm just curious. My guy has only been to 2 shows (before he was mine) and to and from my trainers.
It sounds so cliche, but at this point in me and my horse's relationship, she seems to feed off of my emotions, if that makes any sense. If I'm nervous, she will be amped. If I'm calm, she will be calm.
I think the more they get out, the better. Exposure is good! Previous to this ride I took my mare out alone, just me and her, riding to and from different locations. Doing this probably helped a lot with riding alone during the ride.
Good luck to you! I think you must always be prepared for the worst but hope for he best! My mare was manageable but a handful at the start, and just far more hot than I'm used to seeing her! But as soon as I hopped on and began, she was just fine.