Just an update:
I followed this link and it still works perfect with some additions:
I have Debian Stretch and the winetricks in this distribution doesn't work for the dotnet-installation, because the link to the Microsoft Site is outdated. I downloaded a more recent one from https://raw.githubusercontent.com/Winetricks/winetricks/master/src/winetricks
and this one works fine. It is just a script, so you can download and run it without further installation requirements.
bash winetricks dotnet35sp1
which installs also all the other older dotnets down to 2.0, so SkyDemon can find, what it wants.
After installation of SkyDemon the program starts, but it did not show the menu and tool bar. I played aroud with function keys after generating some route and ended up in simulation mode with Shift-F5. When I stopped simulation mode from the SkyDemon button, suddenly the menu and tool bars showed up and are always present after a restart of the program.
No idea, why this happened, but if you have the same problem, you know, what you can try.
Otherwise everything works fine under Linux/Wine.
If you have problems, please ask. I don't know, whether I can help, but I would like very much to promote SkyDemon PC under Linux.