I know it’s out there in the archives and older posts but it is to damn hot right now in escondido to sit at my computer and search. I bought a 6-2 pavel blank yesterday and used a 6-2 fish temp for toe side and a 5-11 diamond tail quad temp for heel side.
I've made few for myself and placed the side fins the distance from their own "tail" I would have used on a standard shape. That is, if I were to use 11.25" on the front fins of a thruster, then on the short rail the lead fin is 11.25" from that end and the same thing on the long rail. So, let's say you have a keel for your frontside rail and a quad setup for your backside rail, then setup the keel like it's for a keel fish and the quads their appropriate distance from the shorter rail. There's any number of set ups and likely if they're within reason, they'd all work. I used Plus One's set up as a guidline on my last one for the center fin which was offset from center about 5/8" towards the frontside (long) rail and toed towards center. Hope all that made sense!
I would want the exact opposite of you. I would want the single(ish) fin on my toe side and the quad setup for the heel. How did I come up with this? I’m imagining a nice cutback on my heel edge using the quad setup. At the same time, I’m picturing going down the face frontside with a ‘less fins’ feel. But see, I’m describing different conditions which calls for a different board setup than what you’re shooting for. I just read again that you want to come off the top (heel side), okay I can see how you came up with that fin arrangement. Look, there’s only one real way to find out… Other than that, add extra plugs/boxes just in case.