I did an experiment with my Spike CF5 yesterday.
7 psi holding a DIPA
I opened the dump 2 inch butterfly just a bit while I had a 1/2 tube connected to port. Dump with no mess.
2 inch dump valve is hard to control with a head of beer above it. I ended up wearing the trub. Doing same procedure with a half inch line yielded a perfect dump. Last step is to clean the trub that gathers down stream from the butterfly but before the reducer.
I usually get pretty thick slurry existing my Conicals. Farmhouse and Trappist brews are pretty thin tho. Never had a bier bath scenario, but every system/process is different. Sounds like you got it sussed tho Jay👍