Hey guys, need some advise please.

I have a '11 G37S sedan. How hard would it be to fit 19x9 and 19x10 +5 offsets?

 

You'd have to be slammed, stretched, cambered-out, and they'll probably still poke. those are very aggressive offsets even for a coupe, and they've got about 15mm more room than a sedan.
Much better off finding wheels in the +30to+45 range for the Sedans.