I park outside and in winter it's a hassle to take off in the early am because of frosted windows. I don't care it the interior is cold, though warm is always nice, but would do it to clear the windows. Can I just buy a cheap space heater and put it on a timer, or is there a permanent mount version? I have seen some that plug into cig lighter, but that would wear down battery, right? Maybe they have one that is also timered? Anybody have an interior heater for this purpose, and how do you like it?