As Busskipper said, check out the thread on Moab
here. About 2/3rds of the way down the first page is a segment on boondocking locations. Besides the Jeep Safari in April, be aware that many of the school districts in CO and UT have the fourth week of March off for spring break (March 21-29). By that point many families are burned out on winter so they head to Moab at that time. The boondocking on Willow Springs road can get so crowded it looks like a city out there. :(
We usually stay in BLM CG's simply because there are specific campsites so others can't set themselves up right next to you. Does require arriving pretty early (before 10 a.m.) in the day and not on a Friday or Saturday.
