Yeah no problem. Depending on where her cervix is at the time you may have to be careful when maneuvering but once you’re both comfortable there’s no issue going balls deep at 8”.
My ex struggled a bit with doggy but loved it deep missionary or her on top. My wife loves it doggy but is more tentative when on top. Either way sudden motions can catch her out but I think sex and sudden motions don’t go together anyway. Also, she may be fine doggy most of the time but there’s always times when her cervix might be in a different position which makes head on bumps more likely.
As a rule pussies are stretchy and love to be stretched. The cervix is typically the exception to this. If the cervix is really well retracted then you may not hit it head on. Otherwise you can normally work an angle where you just go past it.
The cervix itself feels a bit like a volcano of cartilage. If you go past the volcano opening and press against the areas at the base then it may feel great for her. My ex would cum from this and without me moving at all she could trigger multiples just from the head of my cock being in this pocket. Sometimes her after tremors would start the next one, other times I could help her with a quick kegel or 2 that would cause small contractions in her pussy that would build involuntarily until she came again a few seconds later.