There are accessory power connections available...

The Nomad/Classic and Drifter have accessory wiring available under the seat beside the left frame tube. 1500's have another set under the (left) front of the gas tank and 1600's have a pair in the headlight bucket. Look carefully in those locations and you'll find a double (two connector) negative (black/yellow) and a double positive (white/blue) female connector. These connections are "always on" so only switched accessories should be connected to them.