Honestly surprised no one has even considered
Talisman of Bloodlust specially you firefly. I know you're not fond of proc trinkets, neither am I, but with RPPM, and how it scales with haste as well as the fix to make the procs more consistent means this trinket would have a fairly large up time with the benefit of a
stacking haste buff which would in turn provide more RPPM and consistent high stacks.
Of course the added downside is that this trinket could provide too much haste and get us over the 50% haste mark quite consistently which would mess with rotations slighty.
Either way so far I'm looking at rocking Spark and Talisman of Bloodlust, when I actually get my hands on one I'll test it out and post back here or in the Prot Pala guide and tell you all what sort of results I'm able to get from it.