Set the max carry body weight you want via menu option even though participating in.
Load a save go to: Main Menu -> Choices -> Sport -> Max Have Fat
Pick out the max body weight you want and strike apply.
Accessible max carry body weight choices:
S.T.A.L.K.E.R CoC 1.4.22
S.T.A.L.K.E.R CoC 1.5 R6
Extract “gamedata” directory from archive to your S.T.A.L.K.E.R CoC directory.
Should really be suitable with any other addon.
Does not edit or swap any CoC files at all.