fog lights as reverse lights

I have a 2001 Suburban and I'm trying to tie in a set of fog lights mounted on the rear of my SUV into my reverse lights to give me much mor light when backing up at night. Now what is the best way, and also the easiest way, to wire these up? I know I cant just tie them into the reverse light becuse they need too much current. I know I can wire up a relay to the reverse light wire to trigger the fog lights to turn on when I put the trans in reverse. But here is the main question I want to know. Should I wire the hot wire all the way to the battery? I have a 7 pin wiring harness all wired up for a trailer running right next to where I want to mount the lights. So could I tap into that for a hot wire? Its the factory harness to control a trailer with electric brakes.

It all depends on the the amount of current the lights you are wiring need to operate. If the current draw exceeds whatever the trailer hitch is wired for, less the amount of current your trailer uses during transit, you need to go to the battery.Northstart.....or start it your damn self.

Ok here a bit more details..... I dont tow a trailer very often, and when I do its just a 4 pin harness for the lightsplugged in with an adapter. I'm pretty sure the hot wire in the trailer brake harness is around 12 or 14 guage and there is a 40 amp maxi fuse under the hood for this wire. So I'm guessing I should be fine using this as my main hot wire on my relay, right? Unless I hook up a trailer with electric brakes and use the reverse lights at the same time I guess...(which will be very unlikely, maybe never) One more question. What is the best way to waterproof my relay and connections being that they will be mounted under the truck? I big glob of silicone? Or what?

I hooked mine up (F350) with the large wire in the 7 pin harness (12 or 14 g. like you mentioned). In my 7 pin connector that wire is for supplying power to the trailer for charging also, so there is plenty of "room" for two 55w fog/driving lights, especially if they are only used occasionally. I hooked mine up to a switch in the cab, just in case I need them on while the truck is in park. Did this same setup on my dad's F350 also. Roger