I will say this and I want you to take it for what it's worth; Don't mind me, but I'm just a guy with a big mouth.
That being said, I had a chance to look over your work. After doing so, and reading and re-reading this thread, I'll say this; why not just do it totally free? Let me explain;
MANY of the people teaching "workshops" are imho, no where NEAR qualified to do so. However, they've figured if they get a chick naked, they can charge money to other up and coming photographers and make some money. You are NOT in that category. You are a damn fine artist and I even have a few of your images in my "Inspiration" folder (I didn't know it was you so it's nice to "meet" you) if you're willing to take 40 or even 50%, BOTH imho, are a huge insult to you, so you might as well do it free.
So my point is in a sea filled with people that should be attending classes, you are one that can comfortably give classes and taking 50% and less? on future sales is an insult and one you should pass up.
Again, I'm the guy with the big mouth and I'd MUCH rather do it on my own and keep 100% of profits than give anyone a dime of my hard work. With out you, they move on to someone less qualified and take advantage of them. I honestly feel as though you're being ripped off.