....are you giving or taking or indeed both?
General observation:- Going for diameter with this guy doesn't automatically mean more or less prolapse, it'll also be a combination of the things you do to one another that are stretching the deeper parts of your butt and gut. Sure, without large diameter provided by such a little teardrop, prolapse is less likely to be achievable (as seems to be your aim), but it'll be the mixture of depth and diameter in the same session that help you along.
Me? Well I made my first acquaintance with this little monster 48 hours ago, looking for a great stretch on days where depth is not a priority. I must say ouch, but that good, this is going to be a great session, sort of ouch. Lot of stretch over a short distance, and the little foot compared to its huge diameter will give you something to concentrate on. LLF at your place. Tell us how you get on.
(Prolapse never been an aim or issue here in the house of LLF, you'll need to wait on more answers from some of the other happy butt-feinds to see if there's more advice experience of doing).
Just be very careful, observe meticulous hygeine, keep everything short and filed smooth, it is after-all a part of you that was designed for the inside...As I am sure you already know, all major stretching carries a certain risk, but being relaxed, building up gently, listening to pain and coming back to fight another day rather than rushing will all reduce any health risks to a pragmatic minimum. Be careful and enjoy....just share the fun)