Be sure to check wheel bearings on the trailer!
Personal story here, in 2008 we checked the wheel bearings before leaving for Bonneville, and they were not only dry, they were royally shot. When we removed the hub, the bearings just came apart, upon further inspection it had also gone into the race of the hub. Went down to the local trailer place to see if they could get a new hub, nope it was to old! (The trailer is a 1971) They were willing to sell us a new axle for a mere $1,200.00.
We did find a used hub for (150.00) that the race was still in good condition, found some bearings that would work, and replaced them.
Moral of the story. If you don't think the bearings need repacking, because its a pain to do, just imagine your 30 miles from Bonneville, and the bearing lets go.
From my experience a $10.00 tub of grease sure beats a 1,200 dollar axle!