We talked about it before at this post. You can also see my mods in this picture. I have big wire coming directly from the battery, going to a hefty fuse block that you can just see between the accumlator(?) and the fuse box. After that, it continues to the back, across the back of the engine, and through the grommit behind the gas pedal.

I recommend the thickest wire you can afford, and the shortest run you can manage.

You might be able to cheat and only run a positive wire, and use the frame as your ground.

There's a lot of space in the 'hump'. Most of us put in extra sockets there.

I recommend against using cigarette lighters as plugs in general. If you're going to be pulling significant amps, you should really be using something like Anderson Power Pole connectors.