For those of you that always preheat or preheat whenever possible; what do you use when no AC power is available? I'd like to find an alternative to an expensive power inverter, i.e. possibly a small flame-less butane heater. If your currently using or have successfully used a flame-less butane heater in the past I'd appreciate a link to where I could purchase one. I really don't want to experiment with finding an appropriate flame-less heat gun, so only pass along what you know works well. Thanks.