I tried the q-tip method and found that about 4% cade was right. I made the salt bars this morning (day off, yeah !) and swapped the peppermint for lemongrass since I didn't care for peppermint and cade together. I went with 5% ppo EO usage rate (I didn't factor salt weight at all).
I went with a simple 100% CO recipe with a 15% superfat I found on the internet. I chose to go with 100% oil weight in salt, added at trace after adding the EO (go big or go home).
Boy oh boy did that EO blend accelerate on me. The second I added the EO and mixed, by hand, it went from thin trace to pudding. This is a recipe that needs no stick blending.
Alarmed, I poured the salt in and stirred to incorporate as best as I could. I had to scoop the batter in the molds so there is a lot of texture on the tops.
Sadly, the cade seems to have all but disappeared. Maybe it'll come back once the bar is wet. The bars were rock hard 3 hours after shoving them into the molds, so I unmolded and cleaned them up with a knife somewhat.