We like spending time in the LaPosa South LTVA about 2 miles south of Quartzsite. There's plenty of room to find a site far enough from your neighbors you won't bother them and they've never bothered us. Their is a fee requirement to stay here - $40 for two weeks or spend the whole season from the middle of September through the middle of April for $180. That fee covers your stay, use of the dump station. fresh water and trash dumpsters. Access to a dump, water and trash receptacles makes our stay so much easier. We spend a week boondocking outside the LTVA with a group before we go there but we make sure to arrive with empty tanks and leave their ready to dump before doing anything else. If we use one of the facilities in town to empty and refill, it costs as much as our stay in the LTVA.
https://www.blm.gov/visit/la-posa-long-term-visitor-area