Please excuse my reply Anna as I'm not female, however I would like to respond to your problem.
My wife and I have been in an anal only relationship for 25 years.
During that time my wife, a nurse by the way, has never had an enema.
She considers them messy and potentially damaging.
She also understands that "shit happens" so we incorporate rectal cleaning into our sex play.
She takes Metamucil daily so her stools are firm.
She always sits on the pot beforehand but then instructs me to do a search for any "intruders" before she will allow full and deep penetration.
I start out by massaging her ass and then inserting a lubed finger into her anus.
If I feel anything up there (and I usually do) I tell her and we do a bit more finger play before she exits to hit the bathroom.
Lately I have found that I can help things along by inserting coconut oil suppositories that I make up beforehand.
I mold coconut oil purchased from the supermarket into suppositories and place them in the refrigerator for a few minutes.
I then follow this up by inserting my dick part way - no abrupt moves or deep penetration at this point - this is just for loosening things up.
Leaving these in until fully melted really helps move stuff along

and it has the advantage of being mild & gentle in addition to it's lubricating qualities.
After she evacuates she has me do another digital exam again to make sure she is fully cleaned out.
For some reason she cannot achieve orgasm if she feels there is anything in her rectum besides my dick.
Does it work that way for other women? I would like to know.