Hi Nikki,
Flying over trees is not defensive flying. Obviously this won't help if flying over such terrain is a commerical necessity but if you are prepared to take the risk then I guess you must accept the risk and it's likely outcome - described by Phil above.
If your flying for fun - avoid harsh terrain - it's simply not worth it, give yourself an easy way out.
If you must fly over this terrain - would it be possible to switch to a twin?
With regards your question - I don't there's a correct answer other than avoid the terrain. If you go in, it's gonna hurt.
Take Care,
Cran