Aztruck,
Where did you get your screen height requirement from?
AFAIK, there is no screen height requirement for an all engine takeoff, try finding information for all engine takeoff's in your AFM or Ops Manual. You have to go to the more obscure community noise document.
The 35ft screen height is for cases where you have an engine failure at VEF on a dry runway. The 15 ft screen height can be used for cases where you have an engine failure on a wet/contaminated runway as can reverse thrust.
What other scams can you tell us about?
Thanks
Mutt