Ok... I don't usually make posts like this... but I like to help brothers out..
With my girl it goes like this.... I bought her an anal-deuche. She uses it everytime before we have sex. (we tend to do a lot of anal...

)
It cleans it out the ass-hole really nicely.
On top of that, if she deuches properly, you can interchange between the p*ssy and the ass, without *much* fear of a UTI. I honestly do it all the time. No issues. Just make sure your girl is diligent with her deuching abilities.
Finally.. regarding the clean up... (this is where training comes into play.) for my girl, after each round, she ALWAYS swallows. There are a couple of reasons I like this protocol:
a.) It means there is no nasty left over cum inside of her... which is just gnarly if it 1.) spills out onto the bed sheets later.... or 2.) if you f*ck her again, and feel that nasty goo already inside her!
b.) It's hot. and I feel like a porn-star. bahaha.
.... One thing to note, I trained my girl well. So after I dump a load into her mouth she just swallows it all... then goes to the bathroom, and brushes + mouth-wash.
After that I'll kiss her like 30 - 40 mins later, just to ensure sterility of the mouth
.... Sounds pretty weird I know. But our relationship works wonderful. And yah, just goes to show, that lots of anal is possibile in a relationship. You just need lots of tools (deuches/lubes/butt-plugs, etc.) and you need a girl who is committed to making you happy, and doing anything you tell her to.
-VM