The only push propeller designs I know of are centerline/fuselage mounted which has obvious problems as far as having a tail on the rear of the aircraft.
It appears these challenges lead to all the push propellers I know of either being twin boom back from the wings to each end of the tail (Cessna Skymaster), or being canard aircraft so the tail swaps spots with the engine and the plane is "backwards" (Velocity XL, Rutan Long Ez, Rutan VariEze).
Is it possible or even reasonable to have pusher props on wings? What are the disadvantages? There must be a reason that we don't see every twin prop airplane (with an engine on each wing) with a pusher configuration! Are they just less efficient? Or have some dangerous "edge of the flight envelope" problem? Or present some hard engineering challenge?