Mutt isnt kiddin. Most engines have a 5 min max TO thrust limitation which at high TOWs will be exeeded during the 3rd segment if you unilateraly decide to push the 2nd segment much beyond the AFM height.
If theres an event where a 2nd segment extension warrants a greater height than the 400 (or 800ft) perf value datum:
* and there are no Company-published tables for 1,000ft or the 5 min TO limit
* no obstacle data for 3rd and/or 4th segments
* you dont have time to calculate values taking into account ALL segments from the AFM
then the best idea is to have an escape route in the event of engine-out at or after V1. If no escape route is possible, then as Mutt said reduce your TOW or change to a more suitable runway.
Unilateraly screwin around with nominal performance requirements and not taking into account the potential consequences is very foolish. There could be a goat wandering around the clouds in the 4th segment which the take-off tables may have considered!