Yeah, my BK's have the D-rings (or square-rings as the case may be) but also right below them are two passages where a solid belt could pass through. Those are much snugger and will also hold the sporran closer to your body than the D-rings.

Usually when I sit I pull the sporran off to one side and let it hang on the hip so it's easier to get into and it's not lying on my lap all night. Then when I stand up just pull it back to the front. For me, proper sporran hight is high enough to be off my thighs when I walk without rubbing the bottom of the belt buckle. If that is 1/2" between buckle and sporran I'm fine with that as long as my legs move relatively freely. Usually it's about 3" or so.