This free BLM campground is a little farther north east than you are looking for but if nothing else works for you, this may. 14 day limit. Dry camping only, no services. There might be a campground host, there might not.
The "Veterans of Foreign Wars" VFW/BLM campground on 95 is about 5 miles north of Yuma. (Fortuna Road exit @ I8 in Yuma) Look for the WWII General Patton tank display on the west side of 95. You can't miss it. The campground entrance is behind the VFW building. There is no sign on the road (95) that identifies the campground.
Edit: Yes, 2oldman is correct. Hwy 95 is within 1/4 mile and a well used freight train line is close by. Traffic on the highway is minimal at night but there are a few freight trains that transit the area nightly. The price is right though.
Chum lee