Hi
First, the RJ was somehow certified, so it complies with the "engine out" requirements.
Second, I heard that when performing SHSS (AEO) on an RJ with 18 degs of flaps you can reach the aileron limit with less rudder.
Maybe the Cnbeta, Cndeltarudder, Cndeltaaileron, beta, deltarudder, deltaaileron plots will give an answer.
Cheerz