I don't think your problem is HOW to read the oil level, rather, the problem is the level appears to be too high or having to much fluid in the crankcase.
I too own a 2012, 2500 (30K miles) with the 6.7L and just changed the oil in it about three weeks ago. I put 3 gallons of Rotella T 15W40 with a new filter and find the fluid level to be above the high mark on the dipstick.
Yes I drained the old oil long enough and check the oil level with a cold engine.
My concern is that the DPF/EGR and other BS is not dumping addional amounts of diesel into the crankcase. I hope an experienced forumite can help address this troubling issue.