build the sucker and then see what it needs to trim out.  There is no way to pre-calculate these little trim fixes.  Too many interactions, and they are too small to put accurate numbers on.  Like rake has been well worked out.  Use the best number you can come up with from the various calculators as a starting point.  Wing offset and tip weight work together.  Kind of depends on which you prefer, not that one or the other is demonstrably better than the other.  If half an inch longer on the inboard wing lets you knock off an ounce of tipweight that is probably a good tradeoff.  Then you might have to add an eighth inch of chord to the tip of the outboard flap, or trim the inboard flap slightly.  Trimming the trailing edge looks much better than warts on the tip of the flap and can be nearly invisible.  Just paint the trailing edge black.