In college, I dated a cute, petite blonde for about a year or so. Over the summer, I went to her house to visit. After a shower, I noticed that the medicine cabinet in her bathroom was open, and there, front and center, was the red tube with the old, glass rectal thermometer. I should mention that she was the youngest of 2 kids in the family, and her mom did not babysit or anything. The fact that it was right up front instead of shoved way in the back or in a drawer somewhere made me think (or at least fantasize) that it was still in use-whether it used as intended, or as a toy, I had no idea. I do have to say that she was anal-receptive, as far as fingers and anal sex goes. Sadly, I didn't want to look like a huge nosey perv by bringing it up, and the relationship ended before I could figure out how to introduce the idea.
A few years later, I dated another cute, petite girl, this time a brunette. She, too enjoyed having her anus teased. One Christmas break, I went to her house, and found out that when she travels, she tended to get constipated. After a few days, her mom (an RN) went to the drug store and came back with a package of dulcolax suppositories. The 2 of them walked into her bedroom and shut the door, while I pretended to play video games with her little brother in the next room. All I could think about was what was going on in there. Later that night, having learned from my previous missed opportunity, I told her how turned on I was by the whole thing, and told her that in the future, I wanted to be the one who got to administer the suppositories. She then proceeded to give me a blow by blow description of what happened, so that I'd know what to do the next time. It was awesome! Needless to say, it was a short transition from suppositories to thermometer play, and from that point on, her anus was penetrated on a regular basis.
So, I guess what I'm getting at is that yes, there do appear to be women out there who enjoy RTs as adults. It's just a matter of finding them, and having the guts to follow through.