Installing the wiring looks like a daunting task but as previously mentioned, it really is not that bad (your back may disagree with that) just take one group of wires at a time and follow the plans.
A tip: Prior to attacking the wiring ... very carefully remove the wiring harnesses from the bag and mark where the alignment bands are with a permanent marker.
I found out the hard way the red bands can snag and move which will throw off your harness positioning (perhaps my bands were not shrunk down tight enough because all of mine moved during the install). Actually had an issue where the radio antenna wire was to short to get into the back of the radio without a radical bend so I had to use a 90 degree BNC connector or else tear up the entire center tunnel's hardware to pull the wire back a couple of inches .... so when installing the com antenna cable, make sure there is just a minimum amount of slack at the antenna end to insure the cable will reach the back of the radio easily.
Happy Building,