Curious what you decided to use and how you fared.
I'd used a 3-6-1 V (i.e. 3n-1-2-3w-1) defensive/counter middle with this reasoning:
3 central defenders plus the DMC should stop his attack from the stacked STs and AMCs
The DMC plus 2 MCs gives a 3:2 advantage (possession advantage) at midfield.
AMC plus single ST, attacking middle, to exploit the hole in the middle of his defense, 2 flankers to draw off his defenders even more to the outside, feed the ball to the middle, and make it a legal formation.
Defensive tactic because I'm assuming he's using hard attacking/middle based on his formation and typical mindset, plus I usually end up with more shots and more on target shots using defensive /counter.