I don't know if this will help the discussion or not. I have an older Norcold 682 that worked well at higher elevations. However I noticed that as it got older the slots rusted more an more each year when I wire brushed them for cleaning, allowing more air to enter. I could no longer but a direct replacement burner(Norcold told me I had to buy the whole new unit). I made a slide to go over the burner so that I could adjust the air to fuel mix, like on a WH. I am not suggesting you do this, but during my investigation for a permanent fix I found burners with 6 and 7 slots in them. My thought is maybe a burner with more slots or one that you could be modified to allow more air in for higher elevations would work. Chris Bryant helped me with a permanent fix for mine and may be he can help this discussion also.
