I pulled a wiring loom all the way from just behind the front driver side tire to the bed to wire in some bed lights with no problem. The frame has quite a few bends etc in it, and some internal walls to get around, but there are also lots of access holes along it. Having a fish tape was handy.
Here's a video I did of the whole install. Running the wiring starts around the 8:30 mark or so - I gloss over it pretty quick, but this should give you an idea of the diameter of the loom I ran back there and what it took to get it done: