I agree that under most circumstances, gas lines are best kept under the trailer and pushed up through the floor to appropriate appliances.
Curiously, my Trailswest Campster
originally had the all the gas lines inside
feeding the cooktop, 3-way frig, plus two gas-light sconces on opposite bulkhead walls. Quite a few fittings, and potential leak sources.
In my rebuild, I chose to eliminate all gas appliances except for the cooktop. With only a single hard copper line running directly to the cooktop, I thought it okay to use the original gas line entry point in the shell.