I made a brief attempt to get something going for a U21 season
Yes I remember this, but as you said it wasn't planned out properly and no one was really aware of what was going on.
U21 is harder because you have a shorter time frame so nothing can go wrong if you want to be successful, but it is still possible.
Obviously just 1 or 2 trainees on teams would be preferred, but if the managers dont step up it may become necessary for someone to carry three :)
I think most of the teams on the offsite are in div II, Naismith or will be soon so thats no problem!