Akuperma; no posek has said that lechatchila a jew can put himself in a place where it’s at least not clear what time it is.
Shabbos, tefilin, tzitzis, yomim tovin, davening, shma, everything we do requires time.
There’s also no eretz yisroel, so no mitzvos hatluyos baaretz, no birkas levana… the list goes on