I've got one other thing to possibly bring besides spare bearings. Back, way back, when I was younger and got discharged from the service (Navy) after my two-year stint, we loaded up our [edit: 1963] Falcon [car] and towed our 16-ft Falcon daysailer from Wickford in Rhode Island back to the west coast. We took the scenic route up to Michigan, over the Mackinaw Bridge (on the other side of the bridge the windshield got plastered with mosquitos ... add one more thing: "Off"), visited the headwaters of the Mississippi, took Interstate 2 across North Dakota to Red Lodge in Montana, detoured via Yellowstone over a 10,000 ft pass, then headed for Lake Tahoe via Nevada.
Everything went fine until we were about in the middle of Nevada (read: No where!). I mean miles of nothing. That's when I started to hear a little chirp. Back then those who worked on our cars had a good idea what it was ... U-joint gong bad. Solution was to slow way down, take it easy, and stop at the next town. Fortunately it was a week day afternoon and there was a Ford garage. Pulled into a side street, disconnected the trailer, then drove to the shop. Met the service manager and asked what it would cost to change out the U-joint. Price was regular shop rate, they had the time, and we were out in an hour. Whew!!! Hitched up the trailer and away we went.
That's it: I'd add a spare U-joint to the list, along with spare belts. Vehicles are much more reliable today than they were back then.
You never said what your tow vehicle was or if it was capable of towing the trailer but since you upgraded the brakes one could assume it was reasonably adequate. Personally, I'd tow it, and like others have said, use it as an RV at stops along the way. Interstates have rest areas and places for the semi's to stay overnight so the parking spaces are extra long. If you've got kids and a dog then another option may be better.