I have pulled my boat about 6,000kms one way.
Before the trip I replaced the rims and tires with new and put the old ones in the boat as spares.
I then did a full repack on the bearings and had a spare set just in case.
I also had a tub of grease and the tools needed to replace the bearings if needed.
Like Bill I checked the hubs and tires @ each fuel stop.