Duh!! You said Open Rov not BlueRov. Ok, they do have the cylinder sideways and that is already presenting a round surface.
Frankly strap some more thrusters on that thing
Have you considered making your own hull shape and using stuff like the pressure proof enclosures that are in the store here to put your goodies in? I could see going nuts and having two 4 inch enclosures on the side with a basic catamaran shape. The side enclosures could have your batteries etc. in it and thrusters mounted on the walls of those pieces … then have the two enclosures connected with a flat panel and a two inch enclosure with a clear round dome piece on the front of it. That could be your LED lights and camera etc.
With enough thrusters and power you can push anything through the water.