I live in a SW Denver suburb and, if at all possible, even I avoid I-25 when towing my fifth wheel. And the construction at Larkspur makes it doubly-avoidable. If I were coming from Estes Park, I would follow Thom's suggestion, but only to US 287 in Longmont. Turn onto 287 and follow it south all the way to I-70, then go west to C-470. Follow 470 all the way around the west side of the Denver area to Santa Fe Drive (US 85). At Sedalia, take CO 67/105 to Palmer Lake and Monument. Both state highways are good roads and much less busy or stressful when towing, although winding and a bit slow in spots.
BUT (that's a big "but"), don't drive any of the recommended routes during morning or evening rush hour in the Denver or Colorado Springs areas! You will not enjoy the experience and could even ruin your whole Colorado "adventure."
BTW, Cheyenne Mountain is our favorite place to stay in the Springs.
