Yo gang! (uh) I've been writing a piece of code to fix "mixed face contents" errors and auto-assign correct surface flags and content depending on texture name. I already defined all the original Kingpin textures (you can add new textures or modify existing settings in kpcheck.ini)
This program is an early alpha version, so be careful (the original file will be modified when running this tool -- fortunately, KPCheck always try and make a backup before working on it)! I tried a few different maps (including the source of "Crates in the Hood") and everything went just fine, but hey, I can't be certain it's 100% safe for now.
This tool may be useful if your level editor doesn't support auto-surface assignment (I suspect KPRad does, but I'm not sure) or just don't want to set all the stuff manually.
Grab it here. (48Kb, source and test map included)