Paul, thanks for your reply and yes, rudder is certainly imperative to handle the engine out situation and I plan to have ample rudder area with a very strong linkage and servo. Admittedly, most of my ships can only knife-edge in one direction - when I pull rudder, sloppy "snake" linkages prevent knife-edging when I push rudder.
I have read much of the available material on RCU regarding twins and will follow advise from e.g. Ed Moorman about ample "toe-out" on the wing engines. However, engine placement high/low on the wing is seldom treated. I`m intrigued by the Custer CCW-5 which seems to imply that the propeller slipstream is creating more lift when the prop axis is above the wing chord line.