Kitzur Shulchan Aruch Siman 3 Sif 1
אלא ילבישו ויפשיטו כשהוא שוכב על משכבו מכסה. ואל יאמר הנני בחדרי חדרים ובחשכה מי רואני, כי הקדוש ברוך הוא מלא כל הארץ כבודו, וכחשכה כאורה לפניו יתברך שמו.
My question on this is,
It says (not exact translation) "you should not say that because I am in a room inside a room and it is dark and no one can see me rather you should go under you covers"
So my question is what is the difference between going under your covers and in a dark room?
(I will tell the similarities of both cases)
no one can see you
you can't see yourself
feel tzinus (by doing something different for modesty)
It seems from the Kitzur Shulchan Aruch that Hashem can see you in the dark but not under the covers. (it says וכחשכה כאורה לפניו יתברך שמו. Meaning that it seems that he can see through darkness and not covers)
Which does not make sense because the Kitzur says itself that כי הקדוש ברוך הוא מלא כל הארץ כבודו so he can "see" under the darkness and cover.
So what will it help if you go under the covers if Hashem can see you?
(unless going under the covers is for you or for someone else (not to see you not tznius) and not for Hashem. But as you see above even if that was true they both do the same thing regarding other people and yourself)