Longtime lurker, here. I have recently modified my approach to this style. I used to high krausen dry hop about a third of the DH and then finish off with a bigger near the end of fermentation, followed by a little more in a dry hop canister in the serving keg (if necessary). This was all mostly done at room temps. I meticulously focused on O2 but never really bothered with hop creep (big mistake). I'd do the traditional temp rise near the end of fermentation but never really factored my dry hop schedule into additional rests.
I kept losing batches to what I thought was O2, so I iteratively ruled out any possible O2 ingress. It was always a coin toss on whether I'd get stale beer after about a week in the keg. Once I started putting effort into diacetyl prevention, in addition to the O2 safeguards, my beers got much better. I know this is pretty obvious in hindsight and with all the knowledge out there nowadays, but I was hyperfocused on O2 and lost sight of the d-word. I started to use an intermediate dry hopping keg since my FV doesn't fit in my chest freezer, and now I only dry hop cool after terminal gravity and an extended d-rest.
I use a fermzilla and am able to get it down to 50ish degF in my basement with a bunch of frozen water bottles. Depending on yeast, I ferment at 65-68 for a few days, then let sit at 72 for a solid week. I then soft crash down to 57ish for a good bit of time. Depending on my schedule (2 kids and PhD program), I'll sometimes let it soft crash for a solid week. Then I'll transfer over to a fully purged dry hop keg equipped with a floating dip tube. I purge before I rack onto the hops and right after to make sure O2 is pressure inerted out. Since the keg fits in my chest freezer, I set the freezer to 45 degF and dry hop for 2-3 days, rolling the keg intermittently. Then I crash to 35 and transfer to a serving keg, and donezo.
Things that have really helped the longevity and quality of my hazy beers: Oxblox in the mash. ALDC at yeast pitch AND dry hop. Very cheap additions and provide a good peace of mind. I am considering a half campden tablet at kegging, as well.
Over-the-top, paranoia induced additions that may or may not have helped O2 reduction: Stainless Steel quick disconnects and an evabarrier tubing for transfers. 10 pressure inerts at 13psi each time I want to purge a keg. hop bong that I use when dry hopping in the FV (rare, but I do it sometimes).
Anyways, this post is to basically summarize some best practices that work for me without top-dollar equipment. It's also to get people to focus on O2 AND diacetyl with this beerstyle. I wish I had focused on both from the start. Dumped many of batches for only focusing on O2.
Also, I do have a question for others that dry hop in a keg. Instead of rolling and agitating my next batch, I'm considering just flipping the keg every 6 hours or so. That way the hops will continue to travel through the beer and settle at different ends. I figured this would help increase the contact surface without the risks associated with rousing/shaking. Anyone ever try this with positive results?
Also, if you see any gaps in my approach, let me know. I understand the multiple transfers is risky for O2, but I'm ok with those risks. Happy brewing!