I remember on a post i did, i mention the maximum allowable pressure in inch of water that you should read throught the oil dip stick.
I was told to remove the oil dip stick, put a small rubber hose in the dip stick hole, long enough to be able to read pressure in the truck while you are driving. Surely at the other end of the hose (in the truck) connect a dwyer gage that read 0-10 Water G (inchs of water).
Unfortunately i don't remember the pressure not to exceed. Search my nick and "pressure" you might find it on the forum.
This test will tell you if your rings are due. basicly it tells you the pressue in the crank case.
I personnaly never did the test. I do have some blowby and the front drive shaft is always wet, but i do not loose oil like you do, at least not has much.
Also, if you run a catch can, and the vent on the catch can is not big enough, this may cause back pressure. So what should be coming out from the crank case vent is not and going else where. Therefore you wouldn't be noticing serious oil leak from crankcase vent.