Unless you've got a big tow vehicle (eg, 4x4/SUV), brakes would be a good idea for this sort of weight - I'm assuming each of your scooters is around 75kg, so that's 150kg (330lb) before you add the tool kit...
Going to braked half-axles would require bigger wheels and so a higher floor. So that'll be a Mark 2 design then.....
Andrew