You could just kill all mods and reinstall with just the options you want, and it's incredibly easy to do. Simply delete all files from the root of your SRTT install where the exe is, but leave all the subfolders! Then verify integrity. This will effectively remove all mods and you will only have to redownload ~20Mb of data with the verify. You would then be at a completely vanilla install and can manually install whatever mods you want.
I have a fairly complicated (by my standards) merged setup going, with a lot of little tweaks here & there, which is otherwise miraculously stable; so, honestly, if my options are to trash everything and start over or deal with heavy trucks, I'll just settle with getting flattened every now and then. I was hoping that there was maybe a solution involving either removing or editing specific .xtbl files that might straighten it out.
Thanks for the advice nonetheless!
Heavy trucks are crashing everything on their way even without that add-on. It is part of original Shitface's Weapon Re-Balance Mod. I don't exactly know how to disable that feature, but there are 3 truck_2dr_... .xtbl files in original TTDiS release.
Edit: Shitface's original thread says to delete every truck_... .xtbl file in SR3 directory. Try that.
Ok, I will back those other truck files up first, then try deleting all but the fire truck (as is mentioned in the original thread, I believe).
Thanks for the suggestion! I'll post again or edit this post to report my findings.