For a few decades, and a living, I created and ran hundreds of leagues, both adult and youth. One of the biggest challenges was creating balanced skills level activities when the activity grouping was based on something other than ability, such as age. The age grouping brings a comradery, but unless you find a way to bridge the gap in skills the group cohesion may deteriorate.

Out club rides handle the wide ranging ability levels by having two different ride leader for each ride. The start time is the same for the two rides, and the coffee or lunch stop is in the same place on the route; however, each leader sends out their own route sheet a day or two prior to the ride. The ride leader for big boys and girls sends theirs first with their group riding big miles and climbing a lot prior to the combined lunch/food stop. The "lite" (that is what we call it) ride leader sends out their route sheet, modified for a very reduced level in speed, distance and climbing. We are all together at each start and at the main stop so we all get to get hang out together.

You could do the same if the route starts and stops offer the flexibility of different types of rides.

Good luck, I hope you find a way to make it work.