It's a shame you aren't at the UKOUG conference in Birmingham, as my presentation would have helped you out https://speakerdeck.com/rmoff/still-no-silver-bullets-obiee-12c-performance-in-the-real-world
Basically - you shouldn't be looking to "kill" reports that run long - you should be looking to do this properly. Take the "business requirements" and actually build a system that satisfies them properly. Letting users build content in Production is fine if you have built a solid RPD underneath, and trained users on how to build proper reports with appropriate use of predicates etc. If you're seeing huge TMP files from the BI Server that's because it's pulling too much data back from the DB (see here).
You can configure in the RPD maximum query runtime and maximum number of rows returned.