I moved from MN to AZ last fall, so I think I may be able to help. I hauled my own boy though...
I don't shoe, so that's about the only area I can't help...I would think barefoot would provide a bit better footing. My Appy was a scrambler, so I wouldn't have had shoes on him either way, lest he catch it under the divider; it was bad enough he could have caught a foot somewhere...
At anyrate...number one things are your Health Certificate and Current Coggins...both within 10-15 days of your move. Now, you may not get stopped, or have to stop to have them checked, but if you do, you darn well make sure you have them!
As far as protective gear, head bumper is a good thing, yes...I also like to have the fleece halter protector sets on the halter. I don't like the whole 'face mask thing' as, even with the head bumper your horse will sweat in the heat...I can't imagine that an entire facial mask would be extremely comfortable for them for an 8 hour day of travel. Some people swear by those, but I'm not one of them.
Leg wraps, are one thing I do swear by...mainly because they saved two of my horse's lives many years ago. Even if you just have a thick polo wrap on, that is better than nothing, and can save your horse from metal that may scrape across his legs in the event of an accident. It also gives them a bit of support while standing there for long hours of standing there.
I don't generally put a sheet on, unless I am traveling in the really cool part of the morning; and I take it off as it starts getting warm. I don't want a horse overheating in a trailer, especially because many horses don't drink nearly enough on the road.
When I haul, I keep a hay bag in front of them...again, something that some people think is taboo, and others swear by; if it's a short trip I won't, but on a long trip, I can't justify making the horse stand there for so many hours without it, when that does their digestive system absolutely no good. I've found it to cause no problems, and that it keeps them calmer in the trailer. I've also found it to cause them to drink more during stops, because they have a reason to drink! Invest in an electrolyte to add to her water, as traveling can cause imbalances in a horse, so try to remain ahead of that. Limit grain intake while traveling, especially if they tend to be nervous about traveling...you don't want those extra calories, and you don't want that extra cause for colic or diarrhea.
As far as tack to send along, I would make sure to send a longline, extra leg wraps, halter and leads, and a lined sheet (in case it does get chillier at night). Send her normal hay, to prevent any digestive upsets along the way.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."