I would recommend keeping as many tools as possible in your travel trailer and in your pickup.
I would keep, a tire iron or a four way, a pipe wrench, screw drivers, sockets as well as big enough sockets to change a wheel bearing.
Speaking of wheel bearings you should inspect them as often as possible and make sure they're in good order. I once was pulling a travel trailer and bearings seized and my wheel came off.
I didn't have the tools to replace them so I had to get a road side service company to come fix it. It wasn't fun sitting on the side of the road.
It doesn't hurt to have some extra wheel bearings or a complete wheel bearing hub assembly in your toolbox as well just in case you need it.
I also keep a spare belt and water pump in my truck when going on long distances as well as an extra battery in case my battery in my truck goes dead. If it does I can just replace the battery or water pump and be on my way.
Another thing is keep an extra serpentine belt with you and radiator and heater hoses.
It's better to have these parts with you and not need them then it is to be stranded on the road without these parts and then need them.