Use Ardupilot to maintain the position on an electric boat

ArduRover ArduBoat
1

I’m working to use Ardupilot to make possible to maintain the position of a boat with electric propulsion.
The boat must use only the two truster (2 PMAC motors with SEVCON controller).
I think that this is possible, I need to understand 3 things:

  1. the motor controller have as input 0-5V or potentiometer from 500 to 10kOhm: how can accelerate it? Is correct to use a PWM to 0-5V converter?

  2. to shift from forward to reverse I have a simple analog input (vbatt), how I can make this?

  3. What is the configuration to work only with the truster without steering?

THANK YOU VERY MUCH FOR YOUR TIME