Consider:
Relays allow the 'big' wires close to where they should be located, thus giving those accessories the full power for functional operation. Smaller wires trigger the relay (on- off) from the remote truck cab.
http://alanhorvath.com/54chevy/mad_electrical.php do a search on relays and how to wire them.
if using Alan's diagram the headlight wires come to the (2-hi/lo) relays after the foot switch (& small trigger wires from the cab)
