Well, I certainly wouldn't recommend it, but it would, technically, be possible. You also wouldn't need to an Add-a-Leaf kit, you could probably just get away with a bigger rear block, given that even 4" lifts generally just use a larger block.
The reasons that it's pretty blatantly a terrible idea: the QuickLifts aren't really designed for that sort of thing and there's a good chance you'd just end up breaking them; your CV and UCA angles would be pretty terrible, along with rest of your suspension geometry; the ride quality would be terrible because of both of the first two points; the minute you do anything other than drive over nice, smooth pavement, you'll break something; and for the price of doing the two QuickLifts, the leveling kit (depending on the kit), and then the rear block, you could have gotten something decent for both the front and rear that you could probably actually have fun with.
Other than all that, it's a brilliant plan.