Re: boondocking in northern NM
I'm a bit rusty on the 4wd side of that neighborhood but some ideas include:
Cabresto Lake (FR134A) is fairly short but rough. It's off FR134 from Questa, approx. 6 miles by my quick & dirty with Topo!. FR134 continues east and has some old mining roads off it, particularly at Lagunita Saddle, 16 miles. About halfway, you'll pass FR 597 from Red River. It also has old mining roads. You might stop in Red River; there are some jeep rental outfits that could give you some ideas. It's the center of that type of activity in northern NM. FR77 out of Red RIver also gets you into the Lagunita Saddle area.
From Red River, FR 486 goes to Goose Lake, a very nice (I'm told) tarn at the end of this popular road. I've never driven it; usually been on the ridge above the lake at Gold Hill, which is muscle-power only. Gold Hill has some of the best views in northern NM, IMHO, and appears to be an easy walk-up from Goose Lake based on the folks I've seen coming from that direction. I think FR486 one way, reversing morning and afternoon, but don't take my word for it.
On the other side of Cabresto Lake and the Latir Wilderness is the Rio Costilla Cooperative Livestock Association, which lets you into its country for $20/day. The main road is rough and long, there are good hikes and guided ATV options but I don't think they let you 4-wheel solo.
Santa Fe has limited 4wd options. Jémez has lots of back country roads but I don't recall the old mining routes that are around Red River. It has several hot springs (Spence, San Antonio & McCauley; the town of Jemez Springs has pools; Ojo Caliente on Hwy 285 north of Española (or south of Alamosa, if you prefer) has upgraded since I last went there and gets good reviews; the leader of the pack though not a 4wd destination is 10,000 Waves in Santa Fe.)
I'd volunteer to join up with you but have birthdays in Rio Rancho that have to be attended. As always, all of the forest country has back roads that will be enjoyable if not so challenging.
Philmont is a whole 'nother world. It's close to Red River for mountain travel but also on the edge of the plains, limestone canyon country, old volcanoes, Folsom Man & dinosaur remains. Most of that territory is ranched but it tends to be BLM so there are options. I'll offer thoughts later unless someone beats me to the punch. My computer time-limit clock went off a while ago.
“Often bumpy roads lead to beautiful places. And this is a beautiful place.”
— Dave Martínez