I finally had another go out on the pig this past week.
2' to 4' south swell at C Street, fairly clean and lined up. I rode it with the fin pictured.
Unfortunately, I didn't get too many waves as I had to contend with a bunch of overzealous longboarders in their twenties, but I managed to snag a few.
On my best wave, a nice 4 footer, the board was just flying. The weight of the board combined with the low rocker makes it really go. It felt a little stiff, but overall not too bad. It definitely wants to go with that fin. I will fatten it up, as you suggested. I'm sure that's all it needs.
I also still need to adjust my stance to stand further back as I'm used to riding further forward. I will keep you posted.