Place an oven thermometer inside your Gas Grill (oven) Adjust the burner(s) to achieve your target warming temperature....Place your food inside as you would in your Kitchen oven....Do not place food directly over a lit burner...
PS...Your target warming temperature needs to be 140* Minimum!!!
There is only one Quality worse than Hardness of Heart, and that is Softness of Head.
Kool-Aid...Think Before You Drink