Running outside fridge while traveling

We have a Kitchen Aid Residential refer in the RV that runs off a dedicated Tripp Lite inverter PV1250FC because we boondock a lot. In addition to this unit when we go to Asaska we bring a 17 cu ft chest freezer that we transport in our pickup (has a long bed and cap) and a 3 1/2 cu ft basement freezer. Our dedicated inverter is within 2' of our 6 AGM 6V batteries and runs all 3 units without a problem. I chose that Tripp Lite because of it's HUGE surge capacity. I run a 110V extension cord to the back of the pickup so the freezer is powered at all times when we're on the road, and have wired an outlet to the dedicated inverter in the basement for the small freezer. On the way down from Alaska we regularly see 90 degree temps when in the lower 48 and the fish and our ice cream stays hard as a rock. The RV engine generator keeps the house and start batteries fully charged while we drive so we always begin our stops with full batteries.

We have friends who use a similar freezer in their Airstream trailer and run it from an inverter in their pickup with a long extension. Principal is the same.