I did not understand your first post kitejumping.
Took it as kites were not allowed at this lake, thus you wanted to windfoil instead?
And now there are suggestions about using a kite on a windfoil?
Was a bit confused about your question, but can see now that you want a huge board, but it wont help if the kite can not fly...
Anyways, can not recommend windfoiling at all, when you are not a keen windsurfer - way too difficult and risky also IMO.
If you were an experienced/advanced windsurfer it would be different, and the learning curve as said a bit shorter than kitefoil.
But learning to both windsurf (which can take 5-10 years to get reasonably good) and windfoil at the same time, I dont think is a good idea
I did both windfoil and kitefoil too, but not really windfoiling anymore, way too impractical, really cumbersome, in so many ways.