A windage tray is IMO a necessity when your talking about that much surface area to aerate, the windage from the crank (especially any kind of stroker application) would make the oil pan like a bubble bath.
Most high performance pans have some built in windage control, but could always be improved upon..
If there is no windage control, the oil needs to be as far away as possible from the rotating assy., which in a jet boat application is impossible to obtain...
GT