Quartzsite is the only place I have seen a sign-in on BLM land.

We stayed on that road a few years ago. Didn't sign in with anyone - was there at the spot we chose for nearly a week and saw no one but our neighbors. It may have changed - not sure.

No sign-in is necessary 👍

You do not need to sign in, just be aware of the time limit. We were there for about a week and did not see a ranger come through.

We stayed in Jan/Feb 2020 for 14 days and never saw a BLM ranger....

Stayed out here a week. Never saw any official BLM vehicle. However lots of vehicle traffic of all types, including road watering trucks, belly dump trucks immediately next to the actual American Girl Mine Road. Would say of you don't want to be checked, stay further back from that road. No check-in station here.