I like your design process. I am a windsurfer from Hamburg and in the planing stage. So my thoughts on the ideal shape are biased towards multi use, but maybe intresting for your pupose too:
Shape for lift/planing would be a “planing straight” (no rocker from the back to the middle) maybe combined with a concave bottom. I think your catamaran thought goes in that direction. Here are some pictures with the terminology of all kinds of shapes: http://www.carbonartwindsurf.com/design/boardology/
Nose Rocker: For windfoiling it is often recomended to have a bit of a nose-rocker epecially for the learning phase: If you nose-dive and have a bit of rocker the board will deflect itself upwards again instead of coming to a full stop. Looking at your design, it might be enough for that.
SUP-Stability /or being able to stand on it without stability through propulsion:
The width is important here as well as the volume. Here is another example of a maximum recomended ridersweight given those two factors: https://surfer-world.com/naish-hover-foil-sup-board?gclid=EAIaIQobChMIrcrA8pOU2AIVhkAbCh0orw8NEAQYAiABEgLfJ_D_BwE