You'll be all right. That climb is not to long or steep and it doesn't top off very high either. I don't know where you ride in the front range but this might help. Divide the climb in half as well as the gain. So now,,,, with that in mind, youre climbing just a little more than Lookout MNt and you have 10 miles to get it done rather than 4.
You should be trainning on rides like Deer Creek, City View, Lookout Mnt, Golden Gate Park or some of the Boulder stuff to be getting ready for this tour.
I just did a 3 day event down in that area and it's the Lizardhead Pass day that would have my attention
That was a 110 mile day and it was very hot that day. Start earlier than the tour orginizers say to if you can. You'll avoid more wind and heat if you get started earlier.