My two cents,
1) Tell her. I told my wife, she thought I was weird, and still does. She knows I do it, doesn’t like it (even though she now cums every time we have sex) and our compromise is that she never sees it. I feel much better telling her. While telling her, I did downplay it, 5 minutes in the shower, etc, then she saw my clamp, I said I just put it on in the morning and wear it for 10 minutes while I am making coffee (I am wearing sweats) so it doesn’t take time away from anything. That one is important. It’s aside from the weirdness of it, it’s any wasted time that makes her mad.
2) Lil j also had it right. One night I got in bed, and put on my clamp. She was falling asleep, heard the clicking, woke up and was pissed off. With practice I learned to clamp silently. Hold the clamp open and slide the clamp in as far as it will easily slide in, and lower clamp. Then push it in one notch at a time. Lift the clamp, push, lower clamp, adjust fingers. I have found that it actually helps me get more blood in my penis, by taking 1 full minute to put on the clamp this way.