RE: Spiraling slipstream & pattern aircraft design
The thrust offset-my experience-can be reduced if more power is available - all thrust corrections I have tried - are only needed to compensate for change in trim as speed changes.
This may sound odd -but I will restate it
if speed remains constant - trim and forces remain much the same
also the ligher the model wing loading -the less offset is needed
So I elect to use very little offset and simply set rudder as needed -which is very litle
On the downline prop speed changes ( from pulling to braking) you can mix throttle to rudder offest .
The lateral area distribution helps most in any yawing maneuvers - only tiny yaw produces quite a bit of lateral force
It all goes back to basic : least weight with most power --allows constant speed - with least amount of trim and or power change needed to hold this speed in any direction up /down/ 45 etc..
So-- a light , relatively draggy model with lots of thrust is going to "stay the course" best.
Draggy does not mean a big front on the model that is just silly- typically more flying surface area is best way to add parasitic and induced drag..
If wishes were fishes -a little parachute being towed along would be workable ---(drag placed further aft )