Hello Brian,
Had look at your build problem ,
Is to late to go back to bulk head line up..?.. and is the deck fixed down …?…
laying down keel and frames have let you down ,
if the deck as not been fixed you could try and ease of hull ply and try insert shims or lay second bulk head , the build is quite fair , so if you use the filler method go easy with the sander , you might make your ply skin a little thin, i allways give my hull inside a coat of F/G resin, makes for a strong hull, hope this helps cheers Larry..