Alternatively, a technique is described in the Operations Manual/s for when the 1st/2nd climb limits are too restrictive. Steadily reduce the Field length in increments, thus making the distance to the obstacle greater, and the required gradient less. Thus, whilst the Field limit is reducing, the obstacle limit is increasing. Keep on reducing the Field length until the Field Limit and the Obstacle limit are as close as possible to each other, and Voila!, you've done a reasonable job of optimising the takeoff weight. The big 'sufferer' in all of this of course is the accelerate-stop limit (because you've been reducing the Field length), which need not have been so as the Accelerate-Stop is unaffected by obstacles.
My first question is "do all the crews realise exactly what you're doing".
I'd be concerned that someone who *thinks* they know (but doesn't) will note you've used a shorter BFL than the available runway, and think "aha, I can takeoff from the intersection, rather than taxiing all the way to the end of the runway...."