I have found how to have swastikas on the german planes.
Try to download the following version.Wings of Prey Collectors Edition (2011) [PCDVD][MULTi9][WwW.ZoNaTorrent.CoM].iso
Install the game. start it. When you are asked to install "youplay", do not do it. When you are asked to join any server, do not do it.
go to options, look for the line historical decals, say yes. Done! Now the german planes will depict a swastika on their tails. The history will therefore not be insulted.
I think that this version has been re-engineered to allow the change.