Well, if you've got Necromancers available, try using Haunt Shift. Just haunt shift a porpoise skeleton into the wagon with orders to, if it hasn't seen you for three days, drive back to the last place it saw you at top speed. That way, if it gets stolen, it will seem normal until it's been too long, and then suddenly race off with a base speed of 80'. Yehaw. Also you can order it around that way, again at very high speeds.
JaronK