Going to chime in here on the shooting sports related activities.

Unfortunately, ALL shooting sports activities for the Boy Scouts are now heavily regulated. Even though many of us can afford the Scouts a properly supervised and safe shooting experience, the regulations promulgated at the national and council levels for the Scouting program require that ALL shooting activities take place at officially sanctioned and approved facilities. So as not to disappoint the Scouts with false hope, be sure to check with the local council office.

Don't kill the messenger here...I have faced these hurdles trying to provide some activities for the Scouts in the past.

To the OP. RMNP is a great idea to get the Scouts into an outdoor environment and up to some degree of elevation out of the heat. Camping is likely to be booked unless they want to go back country. NIST / NOAA facility in Boulder is a great science opportunity. Drive them up Pikes peak or Mt. Evans...great for flat-landers. Could also take them up to one of the ski resorts to go zip lining, or alpine slides.

Be sure that they stay hydrated or they are all going to crash and burn at altitude.