absolutely do a normal layup under heels. Double sandwich helps but there is no substitute for fibre where it gets hammered on
but I see wonky rail tuck, sand your your rocker longways to make sure, then re-check where the tuck meets bottom.
Also, make sure that inset layer for the double sandwich sits a little high by 0.5-1mm, else blank compression under vacuum will make it low and you will need a lot of fill afterwards. Double sandwich is not fun.
On another note, jealous as we just can't get blanks machined here for windsurf etc. Too pricey and/or they make you use their foam so they can mark up