Size 3 fins on a 7ft semigun?

I have a great 7ft winter board, but I want to get a little easier paddle to it. I caught some awesome double overhead waves in the winter but it was hard paddling into them. I don't want to get a longer board, like how easy this one is to duckdive, so I have been buying down fin sizes.
So far I've tried (in order) PC7, Fiberglass size 5 and currently has GMB performance core.
The question: will a big wave board work ok with size 3 fins? Thinking of getting FG3 or PG3 fins. Are they too small to hold in big waves or will the gun template take care of hugging the wave wall? I can buy and try them, but rather ask if anyone knows this will work or not.
Here is the board if you want to check it out:
viewtopic.php?f=14&t=13570&p=127317#p127317
So far I've tried (in order) PC7, Fiberglass size 5 and currently has GMB performance core.
The question: will a big wave board work ok with size 3 fins? Thinking of getting FG3 or PG3 fins. Are they too small to hold in big waves or will the gun template take care of hugging the wave wall? I can buy and try them, but rather ask if anyone knows this will work or not.
Here is the board if you want to check it out:
viewtopic.php?f=14&t=13570&p=127317#p127317