UT 313 runs west off of US 191 north of Moab. It leads to both Canyonlands NP and Dead Horse Point SP.
The general rule along 313 is that camping is only permitted in the 'regular' campgrounds.
There are popular disbursed camping areas along 313.
One is along Spring Canyon Road and Dubinky Road. These are 'official' BLM disbursed camping areas. Spring Canyon Rd is easily found by turning north at the sign for the Big Mesa BLM campground on the north side of 313. Probably 8-9 miles from 191. As you drive along either of these dirt roads, you will see numerous smaller red dirt roads leading to disbursed areas. There are dozens of camping areas. Good VZ signal in most areas. Ted is adding some to his campground database.
Teds public campground site