All snowmobiles need to be registered, and out of state riders need a temporary permit. Snowmobiles are allowed on forest service land, need special passes on state park land or recreation areas, and of course are not allowed in Wilderness areas, I don't know about RMNP but I would guess that if it is legal in Yellostone that it is legal in RMNP. Some areas have individual restrictions such as Rabbit Ears Pass where snowmobiles are only allowed on the Eastern side of the pass. My guess is that they are no different than any other group out there, growing up in Minnesota where snowmobiling is a way of life I know responsible riders and irresponsible riders. As in off-roading, mountain biking, boating and so on there will allways be people out there that cause problems and ruin it for the others. Education is about the only way to fix it.
Except as otherwise provided in these regulations or
by Colorado Revised Statutes, no motor vehicle shall
be brought onto any Parks and Outdoor Recreation
lands unless a valid pass issued by the Division is
properly attached to the extreme lower right-hand
corner of the vehicles windshield in a position so
that the pass may be observed and identified. For
an annual vehicle pass, including an aspen leaf
annual pass to be properly attached to a windshield
it must be permanently affixed. Any vehicle without
a windshield shall be treated as a special case, but
evidence of a pass shall be required.
2. No vehicle pass shall be required for:
a. Any snowmobile as defined in section