If you're in doubt, running a wire isn't so tough. A diagram should show the best place to tap (electrically), other than location alone. Match the fuse to the wire gauge, .. both to the load. If you use a std auto-cig lighter 'outlet' put it in-line or where replacement will be easy, they can be fragile. Be sure the lead to your accessory won't be a trip point if you hop on & off a lot. (Put the socket near the accy's mount.)
A lot depends on o'all use, too. If this is for a winch and not just a radio, using a particular plug/socket might be wise to handle high current, last the longest, and IMO too, a 7-wire trailer plug/socket wouldn't be over-kill. You can buy or make up adapters for other plug types.