Full Cap: Tight elastic band in the back = potential health risk?

[LongHairGuy]

Since I went from toupet to full cap, I've been having struggle with fixation of the wig in the back, i.e. nape area.
I tried taping and glueing it down, but it wouldn't work. Didn't stay in place when moving... plus even hurting... getting itchy after 24h and so on and so on...

So I switched back to the option of sewing in an elastic band to fit my head so tight that the wig doesn't move, even if I shake my head upside down. So far so good, looks goods, feels okay.

However: The tighter I measure the elastic band, the more I feel a pressure where it is (obviously). Now, I'm wondering, as the skin and flesh surrounding the skull is full of important blood vessels (and nerves and stuff) that support or brain and body and everything, how do I notice if I take a (long term?) risk by tightening an elastic band half the way around my scalp? (that means: from temple across nape to other temple... the front will still be glued down).

Is there any rule of thumb, just like "as long as you don't get a headache after an hour, you'll be fine all the way in the long run"? How do I know?