If you are looking for something really nice you might try Tiger Run in Breckenridge. It is a condo style park and may not have anything available for a full month (and be a bit pricey too). A beautiful resort type park, just outside of the town of Breckenridge. I think it is up about 8000 feet. It may not help for a full month, but would be a nice stop for a few days. Sites are more than adequate for your rig.
Tom and Barb
'07 Winnebago Voyage 35L
Workhorse W22 chassis FMCA 219315