Tactical CS?

[PlasmaKrab]

IIRC what was used for a lasting effect comparable to tear gas canisters and so on, was to put these CS weapons to a Flame or Napalm weapon class.
This means that the targetted hex will be set on fire, and that the targetted inf unit or others will suffer heavier suppression when attempting to cross it.

You should try raising the WHS rating, maybe that would give you more smoke/crater effect and therefore more lasting area damage, in a way, but I doubt that you can raise the unit suppression without actually raising the kill rate.