I agree with the above for cooler and dry ice or just ice or those blue frozen things. However, DW always comes first!
Depends on your battery bank set-up and its location in the rig, but I would be able to (and would) just grab a couple batteries from the rig and use them to power the inverter for the trip. Put the batteries back in the rig afterwards.
I would even use the rig's big inverter, which can be portable. You can use fat wire with those 600 amp parrot clamps for everything! Works great when I have done it. (Swapping between the 5er and the truck camper)
