Hello,
The OpenROV 2.8 Dev Kit would provide the electronics to control an ROV.
Off the top of my head a couple of things to think about. The ESCs that are mounted on the controller board are made for brushless motors. In my experience bilge pumps are DC motors so you will need to replace those ESCs as well as program them for the application. The other issue you will have to consider is the depth rating of the bilge pump motors.
I would recommend looking on the forum for information on what other users have done and post your questions there as well to get feedback.
-Brian G.