Id be interested in this but you said the pace was a slow 15mph. I think i am more at a 10-12mph pace so i would quickly get dropped. If you drop your pace to 12mph i would want to do it.
I haven't been getting good turn out when I host a slow one, so I dont feel inclined to do them. Ideally rides go from slow/easy to fast/hard over four or five weeks but I guess I will skip the easy nights since no one is showing up for them. If you can get a group willing to ride on the west side then I am happy to make a route. I'm here or on facebook https://www.facebook.com/pages/CubCamp/275268010286
I think your ideal of someone progressing from a 10-12 mph ride to a 15mph + ride over the course of a few weeks is not realistic and certainly not consistent with my personal experience.