Dry hopping under pressure with Fermzilla All Rounder - need advice please

[ILMSTMF]

I have the FZ AR. It's pressure-rated but I have yet to use it for high(er) pressure applications*. Fourth batch into it and this recipe calls for dry hop addition. I already have a plan for minimizing O2 exposure when I dump the loose hops in. I have come to terms with that method but now I'm trying to figure out what would be best practice to follow that.

1) Seal lid. Purge headspace a few times at X psi (what should X be?). Disconnect CO2 supply, do not attach airlock. Any pressure building up in FV will be from natural means. After dry hops have made contact for 3 days, cold crash at 5 psi.

2) Seal lid. Purge headspace a few times at X psi (what should X be?). Disconnect CO2 supply. Connect airlock. After dry hops have made contact for 3 days, disconnect airlock. Cold crash at 5 psi.

3) Seal lid. Purge headspace a few times at X psi (what should X be?). Leave CO2 supply connected. After dry hops have made contact for 3 days, cold crash at 5 psi.

Food for thought
* Pressure applications I have performed (those without airlock / exhaust) - cold crash with bottled CO2 pressure, closed transfer to keg with bottled CO2 pressure (love this).
• Goal is to not "waste" the dry hops. I mean, DUH. We all want to get the best (flavor and aroma) out of this part, right?
• I had the idea that option 1 would be the way to go. The thought being that completely closing off the exhaust would keep the hop aroma in the beer. No science behind that.
• I haven't used my spunding valve yet. In tests, it didn't seem to provide its expected / reliable function. It's a BlowTie v2. Not sure if it's worth experimenting with in a real world application.
• I have performed a "soft" cold crash to 50F under 5 psi. Warming up to 62F for the dry hop addition - 3 days. Then the "real" cold crash happens under 3-5 psi. Thanks @Noob_Brewer for the tip!

I think I'm in the right forum. Mods, please move if not. Thanks.

 

[Jim R]

Maybe I am missing something but isn't the goal of pressure fermentation to maintain a steady and constant pressure of say 12-15 psi throughout fermentation which requires the spunding valve. I recently bought an All Rounder but haven't used it for pressure fermentation yet.

On my stainless fermenter I rigged up a hop bag with a couple sanitized magnets in the bag and some complementary magnets on top of the lid. To avoid any oxygen exposure when dry hopping, I just remove the magnets on the lid which allows the hop bag filled with my dry hops to drop into the beer inside the fermenter without opening the lid. I may try a similar system with the All Rounder some day.

 

[ILMSTMF]

Maybe I am missing something but isn't the goal of pressure fermentation to maintain a steady and constant pressure of say 12-15 psi throughout fermentation which requires the spunding valve.

Perhaps?
In my case, the whole fermentation process wasn't done under pressure. I'm fine with that. At some point, I might ferment hotter and under pressure. But for this batch, I'm just concerned with what I might be able to achieve by keeping pressure in FV during the dry hop phase.
I've since put the spunding valve on it. Paranoia led me to do that. Didn't do much because there was so little pressure built up in there after a day of dry hop contact.