On Demand Propane Hot Water Heater

From a RVer that lives and camps alot for 20 years in Colorado at 10,000 feet - just replaced a 2000 camper that the 6 gallon propane water heater worked fine for years. Think it was a Suburban brand. Recently got a 2023 camper with a Dometic 6 gallon water heater and it will not stay lit above 7,500 feet. It will if i open the exterior cover over it to give it more air. Called Dometic and they pretty much told me now fix for that high of altitude. I thinking of adding another louver on my door to add more air. Sucks that we let mfgs. get away with building stuff that does not work. I was told they typically see more issues with the furnace, however mine works at 10,000. My 2 cents and sorry no help on your exact question.