I've had luck running my empeg on all but the coldest days (<10 Degrees F) with stock Empeg LTD drives installed (YMMV standard disclaimer etc.etc.)

Having a remote car starter may be simpler than the system you describe - let the car warm for 5 minutes on a cold day (or cool on a hot day), by the time you get into it the empeg would be warm/cool enough to operate. It'd be nicer for you as well without all the dash/empeg hackery. Of course if you're into that kind of thing, have at, sounds like fun!

-Zeke