If you slow-poke it from town to town with little intent while staying off the interstates you'll have the best chance. As for my experiences here is a some what best as I can remember list of spares that traveled with me.
1 spare tire...no room for 2 as I could always single out.
2 spare altenators.
1 spare fuel injector
Enough hoses/rolls of coolant and heater hose
Assorted lighting and wiring.
Assorted brake parts.
1 AC compressor incl. Non-haz coolant.
And other assorted spares.
Worst ever repair was the altenator at 2am in front of the duty free store in Canada at the base of the bridge going to Port Huron...normally a 30 minute job was 2 hours in below freezing very windy Sarnia, On.