Not ideal but....
On the 2 outer corners at the base of the seat, attach an eye bolt/ screw.
Run string/ twine around the front and back of the seat, thru the eye bolt, attach them to the forward/ reverse button
That way from the drivers seat pull the string to operate the switch
Another approach is study the diagram from wk2 jeeps, intercept the needed wires and put a remote switch to work with the existing one in the seat