When I wired my toads, 2001 Civic, 2003 Saturn Vue, 2006 Camry, I tap into the toad wiring up front.
I locate the front left, front right, and tail light wires on the bulbs on the front of the car, then solder a female flat four connector to these wires. I then use a flat four cable about 5 ft long that has a flat four male connector on both ends to run between the MH and the toad. (On my Vue, I used a 7 pin connector on the front of the Vue instead of a flat four)
Two issues come to mind if doing it this way:
1) Rear amber turn signals will be rear amber brake lights
2) If you turn on your toad lights while connected to the MH, the toad will actually be supplying power to the MH lights. I have some 10 amp diodes, I'll probably wire these in to the flat four to prevent the back feeding into the MH.
1999 Fleetwood Southwind 35S (Ford F53 6.8L V10) - Toad 2003 Saturn Vue.
It won't do MACH 2, but I can get a sandwich and take a pee.