The trailer has a way of letting you know what it needs.
The boater in me has me carrying stuff most RVers would probably not think to carry. After all spares when you need them are no good stored at home.
A spare fuel filter, oil filter & serpentine belt are carried for the truck. Spare wet bolts, an axle, lug nuts, 2 brake drums with bearings, 2 brake plates with pads, all the lumber, jacks & tools to effect such repairs, spare water pump, a bunch of other stuff like fuses etc all stored away ready if needed.
Just when you think you have it all the rig finds something else needed to be carried.