Has the horse been trailered before or not? Exactly what kind of trailer are you talking about. By your description, I'm picturing something that only a single horse will fit in like this
To me, a lot of the stuff you listed seems like overkill for no longer a trip than it is. Unless the weather is really cold, I wouldn't blanket.
A lot of that other stuff, whether I would use it or not, depends on whether the horse trailers well or not. On a horse that hauls well, I have them in a halter and they have a hay net and that's it. No shipping boots, no poll bumper, no nothing.
If the horse is fine with trailering and it's just you
that you're worried about, remember, most places there is no law against driving too slow
. When I am hauling, I always drive much slower. I leave a lot more space between me and the car in front of me, and remember that you may have to take your corners wide, depending on the trailer.
ETA: Remember to take your time speeding up and slowing down, also go slow when turning and give yourself plenty of time and space to do it gently. No really abrupt movements if you can avoid it.