If you read what the old pilots wrote then you will find that to roll any of the biplanes up to the mid thirties needed both hands on the stick. To roll a 'Camel' the instructors recommended that the stick be moved full aft and full over at the same time applying full rudder in the direction of the roll. If you think about it, and try it on your tranny, you will see that this is a 'flick' maneuver. It is unlikely that a real Camel could actually do an aileron roll, certainly not against the engine torque. These old airplanes, and it includes all of them, not just specific aircraft, were rudder/elevator aircraft, and the models are the same. So, try using a bit of aileron mixed with your rudder, not a bit of rudder mixed with aileron. Forget rates, go for max possible mechanical movement on everything and use the proportional feature of you radio to fly the thing.
Evan.