I'm fine with the series as long as it's on the campuses and not in Denver. That said, CU should dictate the terms and it should be 2 years at Folsom, followed by a year at CSU, followed by two years at Folsom, and so on. I don't even want those games to be yearly. Instead, make it more of a Front Range Series, and include Wyoming and Air Force (it should be 2 for 1 games against them as well). This would make it so we played CSU every other year, and Air Force and Wyoming every 4 years. Based on where things are headed in college football, I think it's time to stop playing the FCS teams, and instead, play one non-P5 game against the local FBS G5 teams. The years CU would be away in this series means they wouldn't have a 7th home game that year, but those away games would be close enough that local fans could day trip to those games, and would have a true 7th home game 2 out of every 3 years. To me, something like this would be ideal and I think it could look something like this:
2023: CSU at CU
2024: CU at Wyoming
2025 CSU at CU
2026: Air Force at CU
2027: CU at CSU
2028: Wyoming at CU
2029: CSU at CU
2030: CU at Air Force
2031: CSU at CU
2032: Wyoming at CU
2033: CU at CSU
2034: Air Force at CU
2035: CSU at CU
and so on...