Yes ,
No problem at all. Just run 2 wires of the required size for the current envisaged from the battery to the socket . I would however ensure (or perhaps even stronger insist!) that he puts an on line fuse in the wiring. This will protect both the battery and this new circuit.
I think the only watch point is to ensure that the cable is routed away from any part of the moving parts and that it is not too close to the top of the heel board so that it could be smashed by the shock absorber hoop rising upwards on bumps.
I have done this modification to power my SatNav in the car. I used a waterproof socket just to be on the safe side.
