im sure you were kidding about racing without a windshield (but if you werent no track allows no windshield)
i use the steel wire from e-brake cables, poke a small hole through the window weld, feed in wire, wrap around a screwdriver on both ends, hit the steel wire with a torch for about 4 seconds and start sawing, it will already be hot from the torch so it takes away the hectic start. anyone whos done it knows about the pain in the ass it is to get it hot.
or you could go buy the heated window tool for 300 bucks. but that would ruin the cost effectiveness