Hard to tell when the seasonal closure of Highway 67 will be lifted. You can check its current status at...
http://www.az511.gov/traffic/McDermott USFS campground doesn't open 'till May 14. You are likely going to find snow up high on the rim. FR 611 heads east from 67 about a mile south of the gas station/convenience store and there are a few campsites that would be suitable for a 30ft 5er, but I'd be very cautious and go in with my tow vehicle first to be sure the road is not snowbound, too muddy, and the campsites already full (I doubt it that time of year if you can get there.
If you take FR 22 to the west, using Google Earth and maps, you should be able to find a nice spot on the rim. I've driven around there several times and some of the nice spots are right on the rim, but you don't see the view from the road.
Good Luck!
