Strange 1-3-2-2-2 opponent

Hi mates, my next opponent has the strangest formation, yet I am not entirely sure how to exploit it.

He plays:
DC,
DML, DMC, DMR
DC, DC
AML, AMR
ST, ST

So he is pretty spread out all over the place, except for the last defensive line.

I just lost my last game against a weaker opponent with a weird formation, and this one is obviously not in the "win against any formation", so I figured I would ask here.

My team contains:
1 DL (injured), 3 DC, 1 DR
1 DMC
1 ML, 4 MC, 1 MR
1 AML, 1 AMR
3 ST

My MC and DMC being the best players.

What should I do?

I would imagine playing long balls would be a good idea against his 7 player midfield?
Have two ST against his one DC? Or 1 ST and 2 AM? Or 2 ST and 2 AM? Are AM bad when he has DMs on the flanks?
Should I defend with four (a DC for the injured DL) plus one DMC?

Thank you!

Is his formation "Definitive Illegal" and thus penalized with 20% possession? If so, will this influence how my formation should look lile?

Just for completeness: I have won 4:0 with 4:3MC:2AMW:1.