Mike
I can see why you are concerned with the way a model, homebuilt or regular factory aircraft would fly if it was in any way asymmetrical. But I suggest you need not be.
Such aerodynamic variations as you describe (well most of them)are unlikely to cause a crash because it is almost certain that the controls would be able to exert more influence than any such asymmetry. Bit like running a car with a flat, you might have to use a bit of skill with the steering wheel but one would expect to retain control
No man made object will be perfect, so what we are talking about here are the acceptable dimensional tolerances. All aircraft drawings will include limits on the variation from perfect that are acceptable. It is not sensible for me to quote actual limits here because they will vary so much between aircraft types and will depend on overall size and so on. Also some parameters are much more important than others - for example if one wing is bolted on at an angle of incidence that is say 2 deg different from the other wing then you might find the ailerons could not cope with the subsequent variation in lift between the wings.
Some very badly damaged (asymmetric) aeroplanes have been safely landed following combat damage, bird strike, structural failure and so on. B747s have shed quite a few flap sections on the approach to land over the years – very often the crew did not realise anything was amiss. A bumpy day can inflict very much larger disturbances on the “equilibrium” of an aeroplane than the sort of dimensional variations we are talking about here.
I had a friend who landed a jet fighter after a wing fold mechanism let one wing tip fold up in flight (about 5 feet or more as I recall) It also jammed the ailerons so he had to use the rudder for lateral control. It was a tail wheel aeroplane and he only burst one tyre landing at 220kts on a 2000 yard runway. But he was a good stick. And they did give him a medal.
Why don't you build a model wehere you can actually try out different size wings and so on? I have a 6 ft model where I can put the one piece wings on as much as one inch off centre and it is still controllable.