I believe on a factory OEM oil pan, the "full" mark on the indicator falls near the top lip of the oil pan. So in theory, if you measure how much water it takes to fill your oil pan to the top, you'll have a good idea of it's capacity.
That said, I've heard some say the purpose of the deeper oil pans is not to hold more oil, per se, but designed to move the full level further down and away from the crank shaft. Doing so allows you to run more oil without a windage problem. So it's hard to say if you still want to run it with the oil level at the top of the oil pan.
The maker of the oil pan will know what the capacity it's supposed to be.
Maybe I'm paranoid, but I don't like the idea of running an engine without a dipstick. I may, after changing the oil numerous times, get pretty confident how much oil I need to add to bring it full again. But that confidence relies (in the beginning) on seeing the result on the dipstick. How will I see the bubbles, if I've added too much and there is a windage problem?