I was also thinking of Blue Arrow in Estes Park. Given the interest from Boulder, Wyoming, and Denver, this might attract more interest. Blue Arrow is "friendly" to Airstreamers and has a lot of amenities nearby (gateway to Rocky Mtn park, restaurants, etc.). I always get the royal treatment when I stay there. I could check with them for 15-20 slots. It's a big park capable of a number of full hookups.
Randy Unter
'66 Overlander
Denver