Help with Achromat VTA

Hey, I picked up a new Technics 1210GR2 (love it) and also got the Funk Firm APM Achromat to replace the stock rubber. This is the one with the glass bottom.

I have the VTA perfect for my LVB250 Concorde cart and I believe the stock rubber mat is ~3cm thick. This Achromat says it's 7cm thick "undercut ~5cm design", can someone explain what is meant by "undercut" and how to correct for the VTA changes in height on the platter?

Logically, it sounds like I would need to measure the APM on the platter and see what the difference in CM is, then crank up the VTA to whatever that number is, then rebalance my tonearm to make sure it's flat, then change the weight of my stylus again. I hate doing it because the damn cart cost $1000 and it makes me SUPER nervous to even touch the damn thing, but does that sound correct for the workflow here?

Thanks!