Thanks for the input man. You're right, there is more than one way to skin a cat... or a leg in this case.
I leg pressed last week on both a flat and 45d press and found as long as I consciously avoided tensing my core, it was just fine.
Current plan is:
45d Leg Press (feet positioned high to target hammys)
Flat Leg Press (feet position low to target quads)
I'd never considered Smith Lunges (I assume the same thing as Smith Split Squats?) but I will give them a whirl on legs day and see how they go.
I really like the idea of this pre-fatiguing and started using it today with humbling results, but I felt like I got more use out of my muscles than the same workout last week.