One thing it depends on is how quickly you plan on consuming the drugs, based on previous experience.
Phenethylamines generally do not have to be stored in the freezer, I don't anyway.
As for tryptamines, they are not created equal. I have no solid evidence but I think 4-HO tryps are the weakest, then 4-AcO's, then 5-MeO's and unsubstituted ones. And it is hard comparing one tryptamine salt with another freebase, freebase tryptamines are notoriously unstable but I think DMT freebase is more stable then some 4-HO tryptamine salts, though I am not sure.
You have access to argon? I find it curious you can get that but still ask these questions.

But you're allowed of course!
I'd only store JWH's, M1 or methoxetamine in the freezer if you are planning on keeping them for many many years.
I guess some of the more stable tryptamines are okay out of the fridge or freezer but I wouldn't try it with 4-HO's and I wouldn't really appreciate it with 4-AcO's either tbh. If at all possible cool them all.
If you plan on doing it out of the freezer, silica packs and argon are a good bet because moisture and oxygen are probably your biggest enemies. I think light is somewhat secondary and temperature determines the rate, but also understand that there are reaction energy thresholds meaning that some reactions occur much more above a certain temperature. The 10 degrees doubling is meant for reactions where the critical temperature is not really near, if I am not mistaken.