I was going to use heli crash sites to create PvP zones around them in my mod PVEZ.
Wreck_UH1Y exists in scripts in 4_World, so I just create 'modded class Wreck_UH1Y' and do my stuff.
For Mi-8 crash sites I had to create new 'class Wreck_Mi8'. Was working fine, but there's another mod that also does the same trick with Wreck_Mi8 (CFDZPlugin mod), so server owners who use both PVEZ and CFDZPlugin got the "Multiple declaration of class Wreck_Mi8" error, so I had to remove my zones from Mi-8 wrecks.
Would be nice to have a Wreck_Mi8 class already declared in DayZ base scripts. It could be just an empty placeholder:
class Wreck_Mi8 extends House
{ }
so mods could extend it and stay compatible with each other.