Does anyone know how to change camera.clip_far in the middle of a map with shade-c (evo) running?

I want to optimize maps by limiting the clip_far at some places in the map where there is also fog, the problem is as soon I change the clip_far I get weird shadow effects (somewhat similar to setting the wrong shadow bias). Normally these settings are set with or before shade-c settings/init.
So I tried simple loading shade-c again but that gives the error "Script crash in sc_forward_destroy" (maybe cause I did not properly destroy the previous shade-c thingy?).
(so far I can't find a destroy_sc or something like that)