Yes, "wing shadow" does cause problems for rear-mounted engines,as well as for the tail control surfaces.
Not sure if "powering out" would help much (anyone ttried it?) either with rear engines or even with wing-mounted - I suspect the wing-mounted engines (below the wing) would tend to give you a pitch-up moment, which is the last thing you need when you do not have the tail to control pitch. I have heard the idea suggested (at least, for tail-mount engines)