another option, which i'm now regretting i haven't done (and have tapped a few +12volts wires already) is install an aux. fuse block in the cab, so only 1 wire (8/10awg, or BIGGER!) would lead from the (+) of the battery to the cab.
a little pricey, but, again, wish i did this from the get-go to clean everything up!
link to a writeup/idea generator.