I have a 2004 GMC which is similar to your 05. Something to consider is overhead console shelve(s) - (1 long one if you don't have an overhead console or 2 short ones to go on either side of factory console). They may be annoying if you are tall - I'm 5'7" and the lower visor helps in the morning and evenings. My shelves came with power plugs on each side, I just had to run wires under the window pillion down to the fuse box. I believe the name is "shelf it".
Also, the bezel (trim) on the driver side dash snapps off by pulling it directly forward, tilt wheel must be lowered to clear trim over steering colum. Wires can be brought through from under dash around this trim easily. There is a blank facea near the passenger side airbag switch that may be drilled to pull a wire through, or mount a tire pressure monitoring system, instead of drilling the dash. That trim is acessable with the bezel removed.
Bob and sometimes - Nina - a Staffordshire Terrier/a SPOILED pit and her kitty Spaz
2006 Dodge SLT 2500 4x4 Cummins Quad Cab w/AT and 3.73
2007 Salem Sport LE 26FBSRV (TH) w/ my Victory Motorcycle in it or a EZ GO Shuttle cart.