How about a piggy back fuse holder, use something like the rear wiper fuse in the fuse box. You don't have to break into existing vehicle wiring then. I got a piggy back from ebay for my other car, nice n neat.
I picked up a switched live from the wiper-motor, the wire that returns the blades to park when you turn them off. Easy to find with a multimeter. Only one live with ign on and wipers off