I recently set up a Maravia New Wave 3 (14.5ft). Originally it had the DRE Rocket Box Slings with said boxes. They are big, heavy and metal right next to knees. I got a Watershed Largo Tote
for use on one side (dry stuff) and a Seattle Sports Frost Pack
for the other side. I had a buddy bar tack strap material and Ankra buckles to the side handles (so it hangs like a DRE Captains bag from the cross bars).
On my Super Puma, I use the Aire / Outcast XL Splashproof Pocket
and weave the outside straps through the floor lacing. This bag can hold 2 5.56mm ammo cans and other various stuff. I also mounted some ammo cans to custom cut piece of 3/8 poly carbonate material that fits next to my cooler / rowing seat. I used 1/2 bolts and rubber washers to attach the ammo cans to the material. A strap secures this to the frame. I can open and close the cans without having to undo a strap. It is like having 3 glove compartments on the boat. Big one on left is family box, Medium one on right is soap, sunscreen, knife, cutting board, frame tool, pump lube, etc. Small box on right is my personal box. I'll post pictures later.