Other than the windshield a good preheat should do it. I usually have the preheater a bit lower down on the vapourizer . @Darryl Durdin
Not sure how much heat you need in Whyalla, but these are great fun. I use mine all the time. Best thing is you don't have to wait until it gets dark to appreciate them.
This link shows relevant information for making a draught shield. Tilley R1/R1A - Draught shield dimensions
thanks for the link Jeff, that lead to some great works of art and just how resourceful people are and being the hands on fella that I am I will follow their leads and post my final preheater. thank you