Im not sure how much longer you have til harvest... and obviously Im not expert. But I had a plant that looked exactly like that (droopy leaves, severely burned, etc...) I fed it Green Light's Super Bloom. I think it's like 12-55-6. They perked right up and all the new growth looks amazing. So I obviously had a Phosphorous deficiency. Im sure this reply is a little late but maybe it will come into use next time
PS,
I havnt read through every post so sorry if this has already been addressed!
I use Beastie, won't be a waste of money, you'll have it when you need it.
The Fox Farm schedule recommends adding it.
I like to water with it near the end, it has no N. in it.
it couldn't hurt, but i think you can just up the nutes with more P .. i forget which one now, but one of those has WAY more P than the other. Just change the ratio.
I'd try full strength, with a good amount of run-off.
Its not a nute burn, Def. for sure, I don't want you to f@ck your plants though, never used to other FoxFarm stuff, just Beastie for a P. blaster.
Long time no talk bro. Wow, you plants sure have come a long way since the last time I saw them. Looken killer man, keep it up. You must be nearly done now huh? The leaves are kinda telling me that. I haven't had a chance to read through everything I missed, but I saw those killer looking buds - WOOT!