I'm not much of a car mechanic, but i was doing a brake job on my F-150, and it was suggested that I at the same time I replace the wheel bearings. Same rough size as the bearings in my BB, though they are roller bearing which are a whole other cat of tough. I was just slathering on the grease, and I put them on re-assembled, and then realized this had been sorta an afterthought type thing. I figured I would hear them wail after a while, but they ran hundreds of K and were fine until the motor seized. The f-150 is like 7000 pounds. Long trips like the one you are contemplating are super huge endeavours but they don't really push the mileage on bearings. The Phil Wood is supposed to be good for 30 thousand miles. If you get anything pretty good it should go the distance, if it can be kept anything like dry.