Don't play short stacked, you give up so much
expected value. If you're playing at a stake you don't feel confident playing with a full buy in at you shouldn't be playing it.
Top pros use short stacks because it makes playing against them more difficult as you need to split your range up into more complex sections because you need to counter both the short stack at the table as well as the other full stacks. Also in most cases the pros will just look to cover the fish at the table, There's no real reason to get into a 100bb cooler when theres a fish at the table paying out like crazy so they often buy in for just enough to cover the fish to prevent that from happening.
As a low stakes rec I don't think there's any value to be gained by playing short stacked, villains are still going to sew chips to you in spots, it would be better to have a full stack to receive all of their gift as opposed to just 40% of it. Also it sounds like you're doing to to protect your roll not because you believe you have a profitable edge in the games you're going to play in with a 40bb stack.
If you haven't spent the time to develop a 40bb deep strategy there is no real reason to look to pay it in my opinion. Plus you're missing the fact that with fewer bbs in your stack theres going to be more 1 and 2 street bets being made that will get your chips all in increasing the variance while you are looking to "Protect" your roll by playing under max buy-in in the first place.
Is there a time and a place for 40bb play? Of course! Are the low stakes that place when you still have huge sections of the game where studying will yield you more value? Probably not.
I hope this helps!