Mine has no notch in the frame. Here it is with no air in the bags sitting on the bump stops and it has about three inches to the bottom of the running boards. It is running on eighteens and has a tire diameter around twenty seven inches. No modifications to the bed floor either, but the IRS diff bolts that hold it in are right up against the wood on the bed
The issue here is 'running down the road' or 'sitting'. At ride height, the running boards are about a beer can's height off the ground. The bag setup on mine is for ride comfort and adjustability, not to see how low it will go running down the road.
If you want to run down the road at three or four inches off the ground I think you are going to need a frame notch. An IRS instead of a live axle might let you side step raising the bed.
Just my two cents