I would like to be able to have a full 5 man academy team+ 1 sub. It would allow for more interraction/gameplay for the academy players and would make it less dull. They could compete in an "academy league or something like that" Of course once a player reaches a certain limit of skill or age they can no longer be part of the academy team.
So you want to build an academy team with 5 roles + a sub?
If this is the case, then my answer, as a player, is no. There's a reason the market is here, otherwise every top team would have a starting roster + 6 players in academy all the time, and they would reign supreme every season because strat >>> skill.
Thisis a response as a player, you will not get an official answer from me.