Interesting report. The gas mileage nose-dives on the 5 above about 65MPH. I would say 25MPG with the racks and load @ 80MPH is pretty good. Where in Idaho are you thinking of heading next year? That's heading towards my neck of the woods (well the southern part is the wife's territory, we are currently more toward N. Idaho).
I have family in Kuna. I was out years ago. I want to stop out so my grandmother can meet my 2 yo daughter