When I used thumb rests, I would get the plastic black ones and use a table sander to lower the profile. It's inexpensive and easy enough to do.
However, when I began to experience right hand cramps lately, my research turned up the movable anchor and the floating thumb techniques. It took a couple of weeks of practice, but once I was comfortable with the movable anchor technique, my hand stopped cramping and I seem to have better control of my right hand plucking technique without the thumb rest. Since my wrist rests lightly on the upper area of the bass, I don't even need the thumb rest when I'm playing the B string (or E, in case of my 4-string Alembic). It does seem that the pressure I was using on the thumb rest (which you alluded to when discussing glue vs screws) was part of the cramping problem.
So it's definitely worth consideration for changing your right-hand technique to do away with the thumb rest. Of course, we're all different and have different techniques and needs to accommodate those techniques, so I"m certainly not going to admonish you or think badly of you if you can't see the alternate thumb techniques being useful to you. I just feel the need to present my case for the physical hand and arm reasons. And I"m living proof, as apparently sooooo many of us here
seem to be, that these issues are more prevalent with age.