[Christ]

That's a pain. Several cars also have them in a pocket in the front bumper where you have to take the wheel off to actually remove/replace it.

You could always put a resistance heater in the bucket that the battery sits in, with a thermostatic control on it... set it and forget it, basically. The small current draw of a resistance heater working in such a small space could probably be satisfied by increasing the charge life by 50% or so. Then again, if there is enough space to insulate around the battery, you'd be amazed how much energy a battery loses as heat just from being used... you'll actually warm it up just by starting the engine a couple times, and some insulation might keep it warm long enough to keep a higher state of charge!