From a RV tech:
There are no adjustments to anything that will make a difference. Removing the protective cover around the burner housing to allow more air to get to the burner might help because the problem is a lack of oxygen and cold temps.
This explains what's happening.
• Propane gas will only ignite when the turbulence from jet causes the propane to mix with the air as it shoots out of the orifice.
• Propane ignition requires at least 2.15% but less than 9.6% propane gas.
• At high altitudes, there is less air so the normal orifice is slightly too large and delivers too much propane.
• If the temperature of the tank is also low, the propane density is increased and the 9.6% limit is exceeded.
Propane Limits of Flammability - The lower and upper limits of flammability are the percentages of propane that must be present in a propane/air mixture. This means that between 2.15 and 9.6% of the total propane/air mixture must be propane in order for it to be combustible. If the mixture is 2% propane and 98% air, there will not be combustion. If the mixture 10% propane and 90% air, combustion will not occur. Any percentage of propane in a propane/air mixture between 2.15% and 9.6% will be sufficient for propane to burn.
Contributed by Ed Daniels