pop down to builder wharehouse and buy a sheet of 18 - 21mm 2.4m x 1.2m shutterply (plywood) about R220 cut to size so that it fits snuggly in the bottom and you will never sit down again. I have the smaller seahawk model and have fished it for about two years and with the plywood bottom for over a year and have yet to fall out. The key with standing is you can pitch and flip into and under thick structure really nicely that is really difficult when siting down.
