And don't carry a water pump, power stering pump, or anything else of that sort...

Carry the fluids...the filters...and some rubber...

I'd just check the oil cooler hoses, tranny cooler hoses, rad hoses and just drive.

If the tranny fails...how would it fail? Completely? Doubtful. B2 piston? So you have a weak/no 1st/2nd gear...you can still make it home. Slipping gears? Its gonna get worse but its unlikely it would leave you stranded in the middle of nowhere...

Remember most of this stuff doesn't fail on the highway..it fails around town when the load is varying and the engine is running hotter (less radiator air flow).

You can easily go overboard but if you are going cross country...the less weight in the car the better.

Throw in some tools but don't put in everything...remember you can do a lot with a car that doesn't require electricity to drive down the road.

Oh and check your tires/spare condition. If the spare is a steel wheel and you have alloys on there..make sure you have the PROPER lug bolts...the steel wheel takes shorter ones than is on the allloy wheels