Good, the tanks are separated from the burners. But, tanks in an enclosed compartment are a safety hazard and violate fire codes. I don't see any vents from the pictures to dissipate any accumulated gas that may leak. So the compartment bottom should be open or expanded mesh.
Altitude should not affect the burner flame. You may need to adjust the burner air vent slightly for a better flame. However, altitude does increase the time it takes for water to boil and increases cooking time. But the direct heat/cooking at the grill would not be noticeably different than at sea level.
Blowing air (wind) can create a draft thought the burner compartment pushing the heated air out thought the vents. For this reason, I would close off the area below the burners to retain the heat, keep the steam pans hotter; and decrease the amount of gas being used. Fresh air intake needs to be provided, this can be provided with a vent in the new bottom just below the burner venturi.
ps. correction about water boiling: at higher altitudes water boils at a lower temperature, thus increasing cooking time. The water will not be as hot as at sea level. This is why pressure cooker work so well. The increase pressure will make the water hotter than 212 deg F. At 7000 ft above sea level water boils at 198.8 deg F.
<message edited by edwmax on Mon, 05/20/13 6:53 AM>