I have a set of powerlet cables that I hook into the front socket. One for the phone (2ft), one for the gopro (a 2ft 90-degree one which works...mostly), and one to SAE. I use the gopro one when it's on the bars recording. I run the SAE one into my tank bag, where I have a waterproof run-through that splits into another powerlet socket and a cigarette socket. The cig socket has a small 2-port USB adapter that I run cables from to charge the phone, the backup phone battery, the gopro, or my Sena bluetooth headset at the same time when I'm not using them. The phone goes into a side pocket of the tank bag or the clear map pocket on top and I close the zippers/velcro on the cable to keep the worst of the elements out.
The only time I've overloaded the socket's 15 amp fuse is when I tried using my truck's cigarette lighter air compressor to air the tires. If I used the extra socket on the run-through splitter or the rear socket at the same time I'd start worrying about the fuse again. Something to keep in mind.