Much simpler and more effective (IMO) to remove the rear spoiler and any forward lean shims. Yes you certainly can run a Booster like that on a Flexon design, BUT you're giving up a lot because the Flexon design does not work like a traditional 2-piece boot that has the boot spine "fixed" by bolt(s) attached between the lower and the upper. The Flexon design has its forward flex controlled by the tongue and as such really needs to have the Booster across some portion of the outer tongue.
This is a thread about Intuition liners so I'm not going to go on about this, but if you're interested in more info you can check out my
Booster modification post for more info.