My concern is that the electric motors (and of course the supporting electrical system) would have to be pretty big. I have not tried to figure out how much horsepower (or kW) would be required for a sprayer with perhaps 100 gallons of water (378 kilograms). I would think we want it to move at least at 3 mph (~5 kph). Have you determined what size motor would be required?
The Bad Boy mower has hydraulic motors. The particular one I converted has a combination pump and motor at each wheel. The larger units have separate pumps and motors. To actuate it, I am using a linear actuator that attaches down inside the engine compartment to the levers that an operator would normally move by hand. I posted a picture here: Skid Steer Mower Overshooting pivot turns. You might enjoy reading through that long thread but be aware that since most of that was written, there have been improvements to the software so some of the issues mentioned there have been resolved.