Some other things spring to mind.
6) What about tie down points. I note you can get ones which are flush with a flip up bit. Would you add lots, maybe 2 in bow, 4/6/8 behind seats to tie stuff down. I am thinking of getting an Aux as well and wouldn't want to carry it on the transom at speed, therefore tie down behind seats in a nice protected bag.
7) Does the fuel tank have baffles or chambers which prevent fuel sloshing about too much? Is this an issue with fuel full/half empty?
8) Am considering Garmin 298C Chartplotter/Fishfinder/Sounder using the CD bluecharts as I fancy planning on PC at home then load up with datacard to take to RIB and flush mounted GPS. Anyone use this combo?