Andy,
I've had similar conversations with coaches, but usually they want to use DH rather than DP/FLEX. I tell them they can, so long as they call their DH a "DP" and list their pitcher as FLEX in the 10 spot in the lineup.
(Usually they want the "DH" to bat for the pitcher, as in baseball...)
When I explain they can use DP/FLEX exactly the same way as a DH (even though that is a limiting way to use it), they are happy.