you would only need maybe 10hp, assuming no steep grades or mud bogging involved. basically, find a modern electric forklift drivetrain and transplant that. 48V AC system probably. Figure battery size based on hours of autonomy drivetrain friction, and rolling resistance of the loaded rig. Aerodynamics won't be a factor. If this thing really only needs to run for 10-15 minutes, you won't need much of a battery. You will probably need a larger battery than otherwise necessary just to get the power density. 60ah at 48v would probably do it if 3C discharge rate capable.