Unless you are boon docking, I see little need for a gas absorption refrigerator, or even an inverter to run a standard one. If you pre-cool. it will last easily for a day of travel. If you travel on consecutive days, a small inverter would be benificial and the fridge would probably run of the TV battery. Most of the modern vintage trucks have high output alternators.
I tell my marine customers that unless they are cruising and without shore power for days on end, go get an apartment size fridge at Walmart for $150. If they are out on the lake for a day or anchored out for the weekend, they are running the gen for AC, so power to the fridge isn't an issue anyway. But... If they insist on buying a $1400 refrigerator from me, I'm not going to send them away.
2013 F250 XLT
I now have a Keystone Outback, but I try to help when I can.
Bitter Gun Owner