I realize your looking for static wreckage as a permanent part of the scenery. In case you aren't already aware: This dated mod by "Charlie" would be more dynamic and allows custom wreckage from the stock p_47d_25 to appear for a time at the point of impact (sorry, I don't have a screenshot). I have all of the files if you want to reverse engineer them to see how it might apply to something custom made. It may also be possible to "mole" an aircraft model in the desired position with a texture alpha to simulate damage (?) without having to create a model from scratch.
From Charlie's Read Me:
Well i just hope people do read the doc lol
Just copy the contents to the root of cfs3
ie....
C:\Program Files\Microsoft Games\Combat Flight Simulator 3
Important User might not be able to join stock games.
to remedy this just delete the BDP file of the p_47d_25.
What this test case does, is allows this type of plane to leave its
wreckadge behind after being shot down.
This also allows The 3d wreckadge to be spawn in the very same
spot it died on.
Over Time in the Dynamic campaign This Aircraft we hopefully
be removed by the AI Recking Crew lol
Hopfuly this mod will pave way for more objects to be written
in.
Charles "charlie" Simpson 2005(C)
Eclipse/AH