Short board

Hi, I would straighten the rails in the aft section. Too much curve there will add a lot of row effect that you want to avoid on a finless short board. Think of a mini-simmonstail.

Also I would make the rocker more continuous. Granted you do not need the rocker once airborne, but water flow do not like complete flat section, I am afraid that your rocker will be a drag to paddle. Do not forget that you are going to displace nearly 100 liters of water on each paddle stroke, it will be easier if the water can follow a curve that gently move it underneath around the board

A tad more rocker in front may help for touchdowns, and progressive enough to avoid brutal decelerations. And more rocker (and/or a step tail) may help to avoid touching the water with the tail.

I can't comment more in detail, I lack experience with rail design for foiling for instance, other than the traditional surf rail do not work well for foiling for the rear/main sections, it tends to engage into turns in response to yaw movements, and you want the board to stay as neutral as possible. I guess plain square rails, or bodyboard-like ones may be better.

I suspect a tri-plane hull may be a good solution to add some bevels to avoid touching the rails in turns, but I do not know how much instability it brings.