Is your wife ever going to drive the truck? If the answer is yes then 4wd is priceless!
Here is why. We were staying at a RV Park in Desert Hot Springs my wife had taken our LongHorn Dually into play Springs to do some shopping. It was near dark I get this distressed call from her saying I am stuck! She took a road the GPS told her to take and it turned from gravel to sand. I told her how to turn on 4wd. She tried to move but it was too stuck. So then I explained how to activate 4 low. She did and drove the truck right out no problem turned around drove until she hit pavement and returned to 2 hi.
So for me that one time paid for the 4wd!