In v4.11 they have added the ability to see the spawn locations in the FMB so now you can see where they are and avoid putting any objects in their way.
This should be great too, I guess, to avoid crashing on mission start. Lately I got one in French Wings Ultimate: couldn't understand what was the cause, but got luckily it fixed only raising by ten metres my flight's altitude on runway by FMB. I expected a new crash of the four planes on runway (which looked to be at zero metre), instead we found ourselves nicely "spawned" (just like eggs and without broking any, lol) on runway, ready for take-off!

Cheers,
GB