Congrats on the retirement! I have 34 years at my employer and can see the light at the end of the tunnel.
I think you've chosen a good truck and now have to make a few decisions about the type of camping you want to do. I went through the same process a while back and you can read my post
here.
I ended up choosing a popup which I hardly know is back there except for the occasional squeeking :). In my case I wanted to be able to hit four wheel drive trails, keep the camper light, pull a boat and make only minor mods to the truck. I bought the Torklift frame-mounted tiedowns which I would recommend and agree with most folks on CG not being too much of an issue if you get a SB camper. I also prefer the cassette toilet as I can dump most anywhere in a pinch and it helps me keep to my nomadic self.
Good luck and, again, congrats on your retirement.
Mike