I built the whole SUP using cedar strips.  I laid the plans on a 14 foot table, covered the various drawings with visqueen and stapled and glued the strips right over the plans cutting each 1/4 inch strip to match the lines on the plans.  I did not fiberglass these sections before stiching and glueing except the deck which had to be fiberglassed on both sides as the plans direct.  So I saved some money but spent lots more time building  and my sup is heavier than the kit built sup.  My reccomendation would be to use the marine plywood you have and decorate the deck with decals or whatever to personalize your sup.  Or you might want to wood strip the deck.  Hope this helps, Eddie   any questions you can email me     [email protected]

I did what you're considering, but didn't glass any of the hull prior to wiring the pieces together. The sides were no trouble, but bending the nose of the bottom panels was a real bear. I think glassing before stitching would make assembly of any of those parts nigh on impossible.

Yes, it's heavier than the kit would have been, but I have no trouble car topping the board myself and I really like the look. 

If you already have the full kit it seems a shame not to use it. Maybe this is a good excuse to build board #2?

Good luck,

Patrick