Thinking about solar to keep res fridge working on the road?

[rsaylor3]

So we just bought a 2020 HC 331rl. Took our first trip and it was a 8 hour drive. I have a wireless temperature gauge and noticed we lost power at about 4-5 hours into the trip. Guessing the two house batteries are not enough. I'm still going to check the truck to make sure it's sending power to the batteries while towing, but I'm almost positive it was and I know it's a small trickle charger at best.

My question to you, is what are my options for keeping the fridge running for 8 hours while towing? We are in Florida so 90+ temps means the fridge for up to 60 degrees by the time we got to the site.

Solar? Another battery? Can I wire the truck to send more power to th batteries while towing?

Looking for the least expensive safe fix. Appreciate your advice and ideas!