Hi Dave, nice looking fin set. I was wondering about fins could fit your board because:
1/ on wide tail
2/ on channeled board
IMO, Controllers is a good choice because they are low, shallow in water so you can dig rails ( double rails if you mind the channel edge). Otherwise, with bigger fins like GL (for example ) you hardly dig the front fin and need to be forcefully to dig the rail, so.... Second positive point is the strong pivot provided by large area of front Controllers fins . This front Controllers will do a strong pivot to carve or at least turn this stiffen board, stiffen because of parallel rails of rectangular shape. The extra width of the tail give some looseness but so few compares of parallel outline ...despite of some channel toe in ...
Try this board with fins as you feel or what Kirk reckons... but keep an eye on this : channels provide you lot of drive already if you push strongly, thrust on them , i mean if you put too many rear fins, you may have the board tracking

instead of gliding free of the wave . IMO, i think: go! on Thruster, forget quad and nubster , channel ridges are already working as tads
I'm expecting your report and feed back, take your time , can't demo a board in few sessions
Find quality waves to demo your board level ,Have fun
Hope you understand me