You can get a 17/4 in an APC prop. For your cowl I strongly recommend
www.pspmfg.com and pick up some cowl binders. Slickest piece of CNC milled neoprene on the market. $3.00 will get you six of them. Male/female grommets that snap together and clamp down on the cowl, secured with a screw and an anti vibration grommet.
Fred, pontoons are very versatile. Definitely two season gear. Joe