I've had to do this also on my 37' DP. I was able to run the cables down the inner cavity to the engine and then from there it was just a matter of weaving and zip tying, keeping it out of the way of moving parts and road debris using additional insulation where necessary.
This was years ago but I'm in the market again to upgrade and I think I may go with a "better" wireless system for the rear and I want side view wired camera's....recently had my windows tinted and looking at the side view mirrors has become tougher due to reflection.
Good Luck...
