I have been able to take a very long dildo in my ass using great care, but it has to be flexible and bendy like the dildo he is using... and not very thick.
I tried it successfully many years ago when I was doing a lot of anal pleasure exploration. I found it to be an accomplishment and novelty more than a physically stimulating experience. Getting around that bend in the colon is a challenge!
For me, anal pleasure and orgasms come from girth over length. Using a girthy toy in the lower sectuon where the prostate resides is where all the pleasure is for me! A fat, bulbous knob on 7 inches is heaven!