Appears I'll be able to steer the craft by differential thrust more easily than I imagined and without the expense of more equipment. For it seems that modellers as ever have got there first, for three distinct reasons:
(1) It's useful for steering seaplanes like the one here without a water-rudder
(2) It can be used to steer model aircraft like the Avro Lancaster on the ground
(3) It can be used to turbocharge aerobatics for twin-engined models
Interestingly I'd occasionally treat myself to wingovers in a Piper Seneca many years ago and also found that a touch of power on the outside helped it around the corner: so what went around has literally come around.
Pilots will be tut-tutting, but tut-tutting each other is what we do best. Technically the 707, Vulcan and Concorde ought never to have been barrel-rolled either...