Decent CGs around the El Paso/VH/FS area?

Yeah, I would not want to try to stay at that rest area DesertHawk mentioned. Very small and tight, no parking lot. You would park (leaning to starboard) right along the (short) access road, with visitors coming and going and parking right by you on the road all night. Maybe use Google Earth to confirm my memory of it, because I was too busy freezing my ***** off using the open air toilets. :)

EDIT to add: Ok, I got curious and checked the satellite view, and was able to find 3 rest areas. The full facility one is not the one I described above, which was somewhere else in west TX. All 3 that I see are still parking off to the sides, but there is a fair bit of room and they have picnic pavillions you can park by. Only the one that DesertHawk mentioned has full services. For just parking, there looks to be a roomier one just west of the junction of I-10 & I-20. There is another one just west of Van Horn. I'm only looking at them by satellite so who knows. Except for the last one I mentioned, there were vehicles parked in the photos so you get an idea of the scale. Maybe the last one was shut down.

Alternatively, you could probably find a roomy gas station at an exit that would let you park out of the way for 5 bucks or maybe free if you bought fuel and/or snacks. We had one place offer that to us when we asked if it would be okay to park back there for lunch. But this was not in the stretch you are asking about.

Moved from Roads and Routes

I keep forgetting about Balmorhea Park, but yes, indeed, it is a nice park. There aren't any shade trees in the rv park part, but each site has a covered table, and at twilight, bats fly out of the tiles on the roofs..interesting to watch.
The pool is wonderful and very big and is in the oldest part of the park which has cabins and big trees.

Always liked Balmorhea State Park (take snorkels if you do), a great place to swim & watch the good sized fish in the deep spring. 238 mi, 3 hours 31 mins from Cruces. One may scuba dive in the deep spring as well. Balmorhea SP WebSite

Just in case you choose Las Cruces. Here's some info on the Las Cruces Area & Southern NM Mexican Food plus camping and attractions in the area. At least try a Green Chile Cheese Burger. Video

Taste of NM Pecans: Stahmanns or Salopek

Off I-10/I-25 on US 70 between Las Cruces & Alamogordo, White Sands Nat'l Monument & Alamogordo Area. This site also has info on Carlsbad......I believe I would stay at Brantley State Park to base to see the area by Carlsbad.

One could exit I-10 at Van Horn (TX 54 to US 62/180) & do an overnight at the Guadalupe Mountains National Park's small campground by the visitor center. Kind of neat area there.

Guadalupe Mountains National Park ---- Guadalupe Pass - Elevation: 5,424' Near Carlsbad Area - TX/New Mexico Border

One can use the War Road Route to bypass the Trans Mountain pass: Use Exit 162 in New Mexico (just short of the NM/TX state line) NM-404/Ohara Rd East, turn right on NM 213 S (War Road), this turns into Martin Luther Kings Jr. Blvd (FM 3255) once entering TX. Take the ramp onto Gateway S Blvd/Patriot Fwy (US 54 S) to TX 376 Turn left onto Woodrow Bean Trans Mountain Rd (Texas Loop 375). Follow Loop 375 to the US-62/US-180/Montana Ave exit (about 12 miles). The US-62/US-180 takes you to Carlsbad Caverns. Not mountains to cross on this bypass. If you take a right on 376, then it'll take you up & over the pass.

If you want to take the Pass, just stay on I-10 on into TX. Take the exit toward Texas Loop 375/Trans Mountain Rd (about 5 or 6 miles from state line)....Turn left onto TX-375 Loop W/Woodrow Bean Trans Mountain Rd it will take you up & over (great vistas up at the top, at a rest/viewing area). Video Drive Trans Mountain

You really do not want to drive into El Paso & do a few city streets to get to & onto very busy Montana Ave (US-180 E/US-62 E). Much worse than a mountain pass.

In Las Cruces: Hacienda RV Resort and Siesta RV Park are the easiest to get to, just of I-10 exit 140. Las Cruces KOA and Sunny Acres RV Park off I-10 exit 135. KOA on the mesa overlooking the Mesilla Valley, Sunny Acres in the Valley & a little crowded. Park Reviews Siesta RV has gravel roads & pads, Hacienda RV has paved roads, maybe concrete pads. Sunny Acres more into town, maybe cramped???

Leasburg Dam State Park is about 17 miles N of Las Cruces on I-25. With Fort Selden State Mon't near by. A young Douglas Mac Arthur called the fort home while his father was post commander in the late 1880s.

A link to on older post: Safe RV Parks in El Paso Area. El Paso is a pretty safe place, No Mexican Drug Cartels Shooting up the place. But have no experience camping there.

No experience, but Mountain View RV Park in Van Horn seems to have good reviews.

There is a Rest Area about 5 miles east of Van Horn on I-10 at about MM 145. But parking is only along the side of the road by the rest area.

Balmorhea SP is a short way off the interstate. We passed by it and thought it looked like not much of anything. But someone we met raved about it. It has a natural spring, I believe. We were on our way past it going down to Davis Mtns SP, which is quite nice, but it's 60 miles out of your way.

From the time line to the NM border, as far as we could tell, it's just small dusty parking lots with a fair number of longer term guests, oil field workers. We drove on to LC. I'd recommend the KOA in LC if you choose to do that. It's up on a hill overlooking town and feels more like a CG than the others, which are more like parking lots. That's not to say the KOA is way out of the way, it's still conveniently located.

All in all, if I had to choose between driving 600 miles or not, I think I'd stay in Balmorhea. Pronounced "ray" not rheeah" by the person who loved it.

we used to stop overnight at Comanche Land RV park in Ft. Stockton, a no frills park off to the right as you're going west. But the oil and gas field workers have filled it up.
We have also stayed in one of the little rv parks in the middle of Van Horn, also no frills, but not for several years.
Instead, we stay overnight at rest stops. There is one about 50 miles before Ft. Stockton, and another one a few miles west of Sierra Blanca (with tepee style shelters)
But the Mountain View rv park on the east end of Van Horn is probably not terrible...it's just going to be a no frills place...but there are a few trees.