Hot Water Heater DeRate

[66lincoln]

2022 212QBW

Camping in Arizona at 5,500 feet the other weekend, and the hot water heater had difficulty igniting. This was our first trip with the new trailer. Same problem each of the three mornings, it would take three or four attempts to ignite. It ignited better if I left the outside cover open; I opine it is getting more air that way but I don't want to leave the cover open. The fridge, stove, oven and furnace had no difficulties igniting.

I imagine that it is just changing out a nozzle to meter the propane flow.

There is no information on the make/model of the heater in my manuals.

Questions:
1. How can you tell if the burner has already been derated or not?
2. How can one obtain the kit to do the derate?