Headlight Switch

One way to do this is to use a double pole, double throw, center off switch. use one pole to power the park/ tail lamps, and the other to activate the headlights. Jumper the outer posts of the switch together on the side for the tail /park, and only use an on/off function on the other pole to run the headlights. Feed the two center pole terminals from SEPARATE power sources. A small breaker for the headlights, and a fuse to the tail/ park center teminal large enough to supply them

You want separate power sources because you do NOT want a fuse/ breaker/ short in the tail/ park circuit to kill the headlights !!!!!

This way, lights are all off when centered, one direction brings on headlights and tail/ park, and the other direction just brings on tail/ park

Take the headlight power off the switch, run it through the dimmer switch, then run each of those outputs to separate (two) relays. One for hi, one for low Put breakers in the power to the relays