It's fine, just stay out of the washes, you may get stuck in them, very soft. In the large areas south of town there are some pretty well defined roads (such as they are). We spent a week there last winter and plan to spend some time there again this coming winter. This is just a few miles south of Quartzsite near La Paz.
2018 Sunstar 32YE
2 dogs, Max & Bitty
Quartsite is pretty much rocks not sand. There are some roads that cross the washes and most are fine if they are well traveled. We have been going there 15 years and never had a problem. If your at all worried stay in one of the LTVAs for 40 dollars for 2 weeks, those roads are well traveled ,so no problems.
I spent two weeks there in January. The BLM land is pretty well used by RVs so you can see where they drive. Kind of solid and packed down. If you go over to the sides where there are little humps of soft sand, you will probably get stuck. Saw one person get stuck. But just stay on the well traveled paths and you’ll find it to be a great experience camping there.