I put a lot of miles on as well, I switched to the vault hubs 3 years ago and am very happy with them. I used to have bearing buddies and always carried spare bearings with me, the trouble is if you don't catch a bad bearing soon enough on a long trip and it damages the races or the spindle the spares do you no good. With the vault hubs I'm running, it is literally one bolt and you can swap out the whole assembly, bearings, hub, rotor, spindle and they're pre-lubed. I paid around $120.00 for a spare assembly for my trailer, much more than an $8 bearing, but I like the peace of mind. They look like this:
Trailer Buddy Replacement Trailing Arm w/ Vault 3,750 lb 5-Lug Hub #43038