I've been coming to lone rock beach for years, its a good inbetween spot coming from canyonlands, monument valley and heading to Zion.    It is dispersed primitive camping and there are no trees so bring umbrellas and easy ups to protect yourself from the sun.   I do not recommend you camp at the beach if its windy unless your in any rv.   Be very careful where you drive it is sand and can swallow your car pretty easily, if you think your getting stuck stop immediately and dig out your tires.   Keep in mind if you are coming here on the weekend or holidays it gets very crowded and is known to the locals as party beach. 

There is water available and a dump station.   The water gets shut off in the winter months.   There is also vault toilets available. 

It costs $30.00 entry fee and $14.00 to camp.   If you have an annual national park pass the entry fee is free.