Why not something a litle bit more representative of the nations involved instead of the individual aircraft?
There's not enough T-Shirt material to have one aircraft representing each nation, let alone decide which one it would be.
Before I post my suggestion, I want to let folks know that I did this based on the national insignias that were in use at the start of the war (ca. 1940-41). This includes Canada's, which was approved in 1924, but didn't see widespread use until late in the conflict. I have assembled them in no real particular order. I just pulled insignias from my chart that I use for my aircraft skins, and applied them on the fly.
If this were the design to be adopted, I am sure that insignia placement would then be decided, arranged accordingly and made official by the powers-that-be.
This is placed on the back of a long-sleeve T (I like long-sleeve Ts - hence the example - but it can be any T folks decide on), perhaps a smaller version of the graphic or just the text
WW2AIRCRAFT.NET could be printed on the front, like over a pocket or left breast.
And if the many colors make it too expensive, it doesn't look half-bad in gray-scale, either