A lovely kiter friend in his mid seventies, is an avid water ski enthusiast for half a decade, kindly gave me an old 'water ski'. Probably older than some people reading this post. Asked a friend to weld up a tuttle box out of stainless.
Height from top of board to foil fuselage is 1250mm.
Weight of stainless tuttle box 3kg.

I still have one of those boards.
the McSki was the prequel to wake boards.
Came out Around 1984/5.
the first water ski to start sideways.
but mine doesn't have the small fin boxes.
heaps of fun to jump wakes.
the foam centre and plastic outer is a problem as if let get hot in sun the plastic would deform and delaminates from foam. So bottom tends to go wavey.
i would say it's too narrow to use as a foil board but good luck

dorothyinste said..
....
Weight of stainless tuttle box 3kg.
...

My new board weighs less than that complete.

All this begs the obvious question, "Why?".

Obviously you don't need a reason. You can do anything you like. But is there a master plan? A benefit to be derived other than the novelty value?

Madness I say!.

You might need to mount the turtlebox further forward.