I see you edited this a few days ago. If you want add to the map outside of Hooper is a hot spring fed thermal pool and campground resort, Sand Dunes Recreation. Not clothing optional but the adults only area is very nice. It's not far from The Great Sand Dunes Nat'l Park which is an adventure of itself. Take Hwy 17 north out of Alamosa about 20 miles.
Bonneville Hot Springs in the Cascades of Oregon is a great spot. I'm not sure what's going on there these days but there is a campground nearby. Cougar Hot Springs east of Eugene in the Cascades is another great place. There's also Hot Springs in California's Owens Valley. All these are out in nature, clothing optional.
Olympic Hot Springs in Washington was another good one! A bit of a hike getting in there, but worth it.
I don't know where in CO you are, but Las Vegas NM has hot springs. It's off the grid a bit. It's not a resort or anything. Just a couple natural springs out in the woods. I used to go all the time growing up. Clothing is optional, at least after dark. Though, come to think of it, I haven't been there in over 20 years, so who knows what it's like today
A number of years ago we were on vacation in Santa Fe. I took a day off and drove thru Los Alamos over to Spence Hot Springs…..a quality soaking site!
Spence Hot Springs is just past Valles Caledera….around the bend on hiway 4 towards Jemez Springs. The Santa Fe National Forest has a post about the Hot Springs on their website. Incredibly it states nudity is illegal…..that certainty was not the case when I was therein the 80’s. There’s an ethical contradiction to require swimsuits for soaking in wild land hot springs!