The argument about boards riding on a cushion of air is I`m afraid just another popular myth.
Its easy to see why when you look at the maths. Board load in region of 200 pounds ??? or more ? Riding on around 10 square inches of water/board (can be less can be more) Required air pressure in region of 20 pounds per square inch to affect things??? Two things
a) Those sort of pressures would never be generated under hull.
b) Even if they were water would simply give and move to contact board elsewhere.
Concaves on hulls are to channel the water not air.
It could easily be argued aerated water is worse for planing on; aerated water does not have the same weight/densitry so would contribute less in momentum exchange. Again its why boards plane slightly earlier in salt water.Board slightly more bouyant and water slightly denser so contributes more in momentum exchange. Board planes deeper over white water .(aerated) (feels great though)
Air is introduced into cavitating props/foils/pumps for different reasons. (to induce cavitation; but thats another headache) Pressures in that are way higher than a board would ever experience.