We do not have a Westport, but there are 2 things that I would look at.
Mate had a similar problem and he changed the fitting at the top where the hot air chimney vents. He purchased a "thingo" thats about 80mm wide by 100mm long with from memory 6 round holes about 15mm diam, this allows the heat to get out but stops wind coming down the hot air passage and blowing out the flame.
The other thing I would look at is putting a piece of tin suitably anchored in front of the pilot assembly to protect it from the wind.
Sounds like what is called a soft flame,burner probably burning slighty luminous which causes less retention to burner.Suggest getting it serviced,this would entail checking pressure and adjusting if require,cleaning of flueway and baffle if fitted,cleaning of injector and burner possible re aligning of thermocouple.Quite often the smallest pressure drop,dust or dirt-carbon build up will cause these symptons.I would not be modifying in any way this generally causes problems.The appliance is designed to work in the conditions you mentioned so I belive a service and fault find by qualified gasfitter should resolve problem.
Agree with Adrian re [Quite often the smallest pressure drop,dust or dirt-carbon build up will cause these symptons.] and his other advice.
If the frig does not run as cold on Gas as 240vac, it could well be a partially blocked regulator, especially if the reg is not higher than the gas bottle valve, ditto a partial block in the flexible tube from Reg to gas bottle, ditto any partial blockage in the gas line, or the tap to turn the gas off to the frig is not fully open.
