Stek - you can get a very good aerobatic setup with a setup like a ZLIN 526 or a CAP- and have the roll couple extremely easy to control -or almost eliminate
We actually liked those setups better than the "all in a line , flying flounder" approach so common today--
There is no secret to how to do it
Take a Zlin 526 ASF - build it to scale except for airfoils -use thin sym sections - and keep weight to absolute minimums

Be prepared to saw the wing in center - to change dihedral - typically you need to reduce it some to where the knife edge flight is quite neutral in roll couple - and then upon application of more rudder than needed for smoth level knife edge - the model starts an adverse roll.
The ZLIN does absolutely spot on axial slow rolls, setup right
Some positive elevator mix is usually needed to get pitch couple right.
You can also use a rudder /aileron mix in the TX but I like to keep that stuff at a minimum
The beauty of these non "all on center line models" --is that you can use the high thrust line to get some terrific pitching , tumbling maneuvers going
The Conical Lomcovak for example - using the high thrust line to an advantage - can produce wild end over end tumbles.
We learned to setup planes for these characteristics long before the mix features in radios hit the market .