Awesome bug! Always wanted to build one of those...
I ran some wiring for rock lights as well as a power line in from the battery to a relay/power box I built through a rather large plastic grommet on each side of the rear hatch. I think I will run the basket rack light wiring through here as well? At the rack I will use a weather pack coupler for easy removal. You might be able to put in something similar?
Either that or drill a small hole in the vertical edge just below the roof line under the hatch lip and use a grommet and silicone? Yet TBD...need to do this soon.