I just want to add that the FP player I describe will have a salary of 43k at 22 years old (cf salary calculator at Buzzer Manager), so the owner will be able to train him out of position easily after is U21 year.
For the FP, I will try to have smthg like this at the end of U21 formation:
JS 3 JR 4
OD 4 HA 5
DR 3 PA 7
IS 9 ID 14
RB 14 SB 15
ST 5 FT 3