Looking good! That battery should be fine to run the fridge overnight. Since you'll be driving most every day, it'll charge back up while you drive and be ready for another night!
As for your plans, I'm not sure the timing, but since you don't have much time, I assume it's coming fast... You may want to consider sticking south as long as possible, then head north to Yellowstone... The park is closed to wheeled vehicles all winter, and already closed to snow coaches too. The roads don't open until April/May. There's a schedule here:
http://www.nps.gov/yell/planyourvisit/parkroads.htm
If you're coming over to see Grand Canyon, there's other stuff nearby that's also interesting... Valley of the Gods is a great place to spend a night. While there, drive up Moqui Dugway, and out to Mulie point. Monument Valley is right there too, so you can see the "Forrest Gump" road, and all the sights.
Driving across Colorado is never bad, just make sure your intended route is open. They try to open most paved pass roads by Memorial Day, but most of the trail passes open later. The drive from Durango to Ouray is pretty wild. Ouray has a nice hot springs you can take a soak in for cheap too.
Try to make it through Moab and do a little sight seeing and hiking. (Visit arches, at least.) Spend a night camping out Kane Creek Rd, and drive up to Hurrah Pass for a nice view. (Ledge campgrounds)
If you end up over by Salmon, ID, hike up to Goldbug hot springs. Very nice natural hot springs. (Or it was when I was there, ~10 years ago...)
Ok, that's enough... I best get to work!!