Okay, I just backed up a sec. You've never hauled before, right? And you're going to take a long trip with a loaded trailer and sub-optimal truck? And you don't know how bud is going to handle that kind of thing, especially when you've been having issues. Traveling can be very hard on a horse.
And it take A LOT of time behind the wheel to get used to hauling. Even if you've hauled before, a new setup takes times to know.
I know, party pooper! I would take small jaunts in nice weather to familiar territory for some time.

Average, for horses with some experience at this level