The drive from the town to the trailhead while short has been damaged due to the excessive rain in the area this summer. There had been 8 days of straight rain before we got there. There were several "mud crevasses" along the road that you need to watch out for, and in the 4WD section there is a big mud gully that some 4WD vehicles chose not to conquer and parked to the side of it instead. This spot is about .5 mile from the actual trailhead.
Given the condition of the road, we car camped before the mud gully, and then navigated it in the morning with more light and parked at the trailhead. We got a later start then we had planned (about 7:30 a.m.) from the trailhead and knew we were going to be in for a long day if we wanted to do both peaks. Fortunately for us the beautiful weather made up for all the previous days of rain.
We arrived at Willow Lake around 10:30 a.m., and then made our way up the very long and steep slope to the Challenger ridge. While we were climbing, a woman knocked a huge boulder down that came cartwheeling toward us. We had to run to get out of the way and bruised some legs in the process. This was very frightening, as we didn't anticipate any loose boulders.
Once at the top of the slope, there is traverse that the Roach book doesn't mention followed by a climb through a notch before you get on the actual ridge. We had encountered about 10 people coming down that said this traverse had too much exposure for them so they were turning around. We couldn't fathom what this would be since the book made no mention of it on this Class 2+ route. It turns out that on this spot, the exposure is extreme, made more difficult by the wet mud on the bottom of our boots. There is about a 20-foot section where handholds are hard to find, and you pretty much have to hug the rock to get by. Then the notch is similar to the spot between the Trough and the Narrows on Long's Peak (minus the metal spoke). I had to use my knee to hoist myself through this spot since my legs aren't long enough to reach.
The rest of the ridge is a straightforward Class 2 ridge-walk to the summit. Once there half of our party decided to return to the car, and even though it was 2:00 p.m., there was not a cloud in the sky so two of us decided to push on to Kit Carson even though we knew we wouldn't get back until late.
We were very pleasantly surprised with the straightforward and easy route over to Kit Carson. There was nothing difficult along this route and nothing even came close to the difficult spots on Challenger. Kit Carson Avenue is a solid trail, and then the scramble up the gully is well marked and we popped up on top easily. If I had to reclassify these peaks, I'd call Challenger a Class 3 (with caution) and Kit Carson a Class 2.
On the return, we ran into someone who gave us a different route instead of going back over Challenger. This is the dotted blue line in on the Roach map that stays below and to the right (east) of the Challenger summit. It is just boulder hopping across the lower part of the mountain until you reach the slope coming down off Challenger. We didn't actually find the exact slope to go down, but there are plenty of spots to choose from. Willow Lake is in plain site the whole way so you can't get lost. This saved a lot of time and effort. The only difficulty was the persistent wet mud on the bottom of the boots, which made for slow going on a steep descent.
We arrived back to the lake around 6:30 p.m. and knew that it would be slow going back to the cars when it started getting dark. However the trail from Willow Lake to the cars is straightforward and contains many switchbacks. There are three creek crossing that you do via logs, which we were able to navigate in the dark. We didn't get back to the cars until after midnight and were fortunate that we had good weather to accomplish this 15-hour day. We camped for the night, and then ate a hearty breakfast at the Shambala House the next morning.
Note: To avoid the long day we had, you should either pack into Willow Lake and start from there or start very early in the morning. This is an extremely long and arduous day, and you must have a perfect weather day and be confident in your ability to navigate trail in the dark before committing to doing both peaks in the same day from the trailhead.