Rrae,
I had my first battery implanted in my right upper butt cheek. All the moving around, standing, sitting, etc seemed to have allowed it to move around. It turned sideways a bit, and made sitting almost impossible. That's when I had it replaced and the dr. moved it to my right side, just below the natural waist. It would have made wearing anything but jeans that fit at the natural waist impossible. Of course, I had a MRSA infection set in under the battery pack and had it removed after a couple of weeks. My pump is placed in my back just below the natural waist. So far I can wear sleep pants. I haven't tried anything else as I'm still swollen from the surgery. It's only been 3 wks. lol. I don't think getting it in the butt is a good idea. IMHO if I had to do it again. I would insist on getting it in the side. When I got my first one, I really didn't have that much information on it. Only what I got from here and the book the company gives you.
Hugs
Mary
PS. you are really smart thinking this all the way thru. THese are things most ppl don't think about, (like me), and pay for it later down the line.