Ok. I just re-started a new game and tried out the different combinations. I rebuilt the bash patch, then ran BOSS and adjusted the load order a bit.
So far, what I have added on top of baseline STEP is:
1. RLO
2. CoT
3. Duel (I tried Duke, but I perfer this one)
4. Skyrim Scaling Stopper
5. Empowered Magic
6. Morrowloot (placed it after SSS to get its benefits)
After 2 hours I have no CTDs, but might be still too early to tell.