My kayak: Dagger Alchemy 14L
Pelican 1430 case with two 24" flat bungees
D300 with 70-200 f/2.8 VR and TC14 fits quite nicely with hood reversed. Note folded towel in bottom of case for cushioning.
Bungees attached to safety line running along top edges of kayak.
Case open when in safe area and ready to shoot.
Open top cover makes for nice holding shelf when you need your hands to reposition the kayak.
Kayak with Pelican case mounted.