I'm currently using a 3-5-2 with a Ball-Playing Defender_Cover (Diego Reyes of Porto, whose primary position is Defensive Midfielder but operates as a CD for Mexico - in FM, at least) in the middle of two Central Defenders_Defend.
I originally had Reyes pushing forward more, but he would constantly step-up at the wrong time and leave the other two exposed to through balls and runners from deep. I generally have the team pushing up - relying on my five-man midfield to create enough opportunities going forward to massively outweigh the few (inevitable!) occasions that we get caught out in the defensive channels. Reyes, in particular, is excellent at interceptions around the halfway line and he's also very good in the air.
My flat midfield five is made-up of: WM_Support; DLP_Support; AP_Attack; BWM_Defend; WM_Support.
The front two are: AF_Attack; False9_Support
Always play the Advanced Forward on his preferred side; right-footers on the right, left-footers on the left. This is important in relation to him making runs into the channel and the relative position of him - and his preferred foot - in relation to the goal and the closest covering centre-back...
...If the AF is on his preferred side, then the player himself is between the centre-back and the ball and can shoot into the top or bottom corner of the near side of the goal, or across the keeper into the far side; if he is on his weaker side, there is nothing between the defender and the ball and shooting into the far corner is very difficult whilst on-the-run, so easier for the goalkeeper to guess the right way and make the save.
Similarly, a left-footed False9 with good long-range shooting ability who operates on the right of the front two, can open his body up from the edge of the area to aim at the whole goal. Again, more difficult if he is trying to do the same thing from the same position on his right foot - where it is also more difficult for him to shield the ball from any defenders in his wake.
For this reason, the four forwards in my squad are in rotation pairs; the two left-footers play together or the two right-footers play together, and I switch the AF and F-9 positions to suit, match-to-match. When I do have to couple a lefty and a righty, the Advanced Forward plays on his preferred side and False9 just has to make do.
Not exactly what you were talking about, I know, but while I was sharing (and in honour of how hot it is outside)... (H)