It make sense to think about water like one of the priorities, to have mean to drink clean water.
It is good thing that you are not alone, that you have two men that you can trust.
That kind of distance would be almost impossible to cover in case of some serious SHTF event. I would consider to brake that trip in some small parts, with lot of “stations” ,maybe to give a thought about that, to have as more possible (and secure) stops as you can.
Think deeper, it is more likely that you gonna need camping gear (walking many miles on foot) then extra fuel most probably it is gonna be impossible to drive all the way, dangers, low profile etc)