There is a very good reason why the tires/wheels tuck under the fenders. If you plan on doing any severe off-roading you want to be aware that your up travel will bring the wheels and tires into the front and possibly rear fenders.

With the added travel of a lift and extremely offset wheels there is the very likely chance that you will do damage to the fenders and the bumper. (or the plastic bumper trim at a minimum).

I personally know of two instances (although it was jumping thus bringing the suspension travel through it's full cycle) that the off-set of the wheels coupled with the limited space and extended travel practically blew the front fenders off the truck from the bottom up.

You either need to do some extensive trimming in front or go with fiberglass fenders and at a minimum go with bumpstop extentions to limit your uptravel in the rear as minimal preventative measures.