BEagle
I agree with you that an EOA should be published for each aircraft but it is not.
I think that this is because the makers of these aircraft feel that a lot of the "variable factors" are out of there control and the legal implications of publishing such a "hard data" would lead to them being taken to the cleaners by a sharp lawyer.
This being the case the best way to protect your student is to get them to find there own personal ACH.
You should remember that light twins should be treated as single engined aircraft that can continue flight after an engine faiure if flown properly and that in some phases of flight the best course of action is simply to close both throttles and find a field.
In terms of flying skill and airmanship to fly safely a light twin is much more demanding than the B737-800 that I fly for the day job.