Don't let the theories get in the way of making your Katana fly .
First -remember the task at hand.
That is: how big is the plane and what do you want it to do.
On small models -such as your Tigre 60's, wing loading is kept fairly light for best results -you could change the airfoil from 10% to 15% and see little performance difference
Also you could taper the wing some or keep it a rectangle -with no noticable differences in performance.
If you put in an extreme taper say 4-1 the results will change but -if you reduce the wing loading quite a bit as you make this change - you may find the model flies very well .
Trying to randomly pick a characteristic from a large 500,000 cargo plane, then apply it to a 5 lb model is absurd.
You did not say how large your Katana was to be -so absent that - it is hard to correctly assess how good/ bad either wing planform will perform. Having done /flown various Katana's - they are aerobatic setups and less wingloading is always better for powered aerobatic models full size or tiny models .
That is one hard,fast rule.
Bottom line -it is physically impossible to get your Katana too light and the lighter it is, the better it will fly AND the less critical it will be to CG positions .
CG does matter of course - but if you can't tell that a lighter model has a broader effective usable cg range - you simply have not tried enough size/weight combos.
If one flies the so called 3D models , it becomes very clear that flying with vectored power permits CG ranges that are completely off the textbook ranges for controllable flight -yet -these models fly extremely well.
I started modelling flying free flight and control line stuff, a loooong time ago so I do understand CG - both from a practical and a theoretical standpoint.