This entire thread has it wrong (except for Shug, in part). A true structural ridgeline sets the hang angle by being a rigid member of the suspension system. Forget twisting the ridgeline! That's for non-structural (i. e. "indicator" ridgelines). They have their place, and most of you use them, but the OP wants to use a structural ridgeline to allow him to hang at a specific height. He gives good reasons for doing so.