Some bugger stole my Occys (like I need more fins)
Yep I recon do that M7 side G5 rear/centre, you will be amazed how much difference that will make. M7s have the inside foil as well and that will make it looser as well.
I just had a look at that board, you can set that up as a quad!! Get some GX--Q rear set with the M7s and you are done!!!! For big boards like that I recon a quad set up is the way to go!
I was in QLD recently and I borrowed a 6,8 7S fish. First surf on it it was set up as a thruster, it went okish but didnt start any fires. Next day I took the centre fin out and put in some rear quad fins, the difference was chalk and cheese. The quad was miles better, faster and looser!!

Go the quad imo