RE: Rudder offset or not?
Rudder offset DOES work! It is not, however, needed or wanted on all planes. Take flying wings, for instance...any rudder (offset or not) is pretty much ineffective as the moment arm is so short. Besides, any C/L airplane going 100+ mph is going to stay out on the lines regardless. What little offset the engine has on a combat wing is needed mostly on launch.
A rudder, fixed or not, is a control surface and as long as there is relative wind acting on it, it will make a difference. Engine offset, line placement, AND rudder offset should should work in harmony...not against each other.
Putt Putt is correct in as much as the effectiveness of the rudder at slow speed. When an engine in the tractor configuration is honkin' up front, the rudder is working. And when the lines are a little slack in a wing over, the line placement is not as important as engine and/or rudder offset. But if one is using long lines or heavier gauge lines, tip weight and line placement will play a more important part.
All the methods we have traditionally used to control line tension work. Some planes, however, fly better without having to resort to every single one.
The bottom line...do what works best for the particular plane your building/flying.
Cheers,
Bob Edison