I have had 2 airplanes with 8 degrees of out thrust and both would fly without rudder engine out. The Twin Stick in my avatar has 8 degrees and it will do acro on one engine. The best single engine twins, except for a pusher-puller, of course, is a twin fuselage plane. The fuselages channel the air flow down to the rudder, I think.

I also have a TwinStar. It has some out thrust and flies OK engine out, but not to where you can ignore the situation. When mine gets old, I may chop off the cheeks and put in 8 degrees just to see how it handles.