A rear battery does not have to take up the spare tire well. I use mine as a storage area for tire plugs, a quart of oil, a DC air pump and a few tools. A blow up Ursula doll is optional.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.