RM, reverting to the question; the 146/RJ has a good range of performance options with a choice of 3 takeoff flap settings. Choose the lowest V1 according to field length / obstacle limitations.
Some RJs had an optional modification ($$) enabling 33 flap take off, with lower speeds, higher weight. This might only apply to the RJ 100, and specifically considered the old, shorter LCY.
I strongly urge avoidance of exotic fixes for issues perceived as increased risk or a good idea; more often change creates problems. Heed Chesterton' Fence -
https://fs.blog/chestertons-fence/
The dump suggestion - not required for certificated performance; in addition to proof of reliability, enquiries might question if it was tested in all take-off configurations.
Similarly avoid the DER process; some very bad - downright dangerous experiences.
More formal certification routes could open a can of worms; was Vmcg reassessed for the 'fat' tanker. I recall removing the baffle across the gear bay - reduced wt, had interesting lateral/directional qualities, thus any changes around the gear doors might influence side force.
As for the RTO hazard, with fading memory there were few, if any engine failures in the high speed portion of take off. Alternatively tyre failures at high speed, inappropriate RTO and overrun, are recalled.
The incident @ page 15
https://skybrary.aero/sites/default/...shelf/1326.pdf involved a RJ, a challenging situation; that Capt also said that if it happened again on a short runway he would continue the takeoff - such is experience.