In 2000 I took my kids out West on a similar trip. Mt Rushmore, Yellowstone, Tetons, RMNP, into Utah through Moab, Monument Valley, . I felt like Clark Griswald. We had stuff tied on top of our 96 Astro van and hanging off the back in a hitch haul. We seriously over packed. We packed for several weeks of camping without realizing they have grocery stores in the west too. I lost about 2 mpg compared to usual. A lot of that was probably more the weight than aerodynamics.
If I were going to do it again it would be with a clamshell type of carrier. After a few days we figured out what we really needed. What we could throw in the trash we did. The stuff we didn't need, and couldn't trash, went on top and wasn't touched again till we got home.
I've made the West trip a few times before. The last time was 2008, when my wife, 2 boys and I car camped in my Yukon. We kept it as bare bones as possible. But, a tent and sleeping bags alone eat up a lot of room and we were pretty crowded and had to keep our stuff perfectly organized. After every night's camping, we had to unload the truck and repack it exactly. Now that the boys are teens and take up more room, it would be nice to not be so crowded.
The last TIME we drove around 7,500 miles and got about 16 mpg. So, I figure every 1 mpg lost would cost roughly about $100 more in gas.
