I (M23) have trouble with poo while performing anal masturbation

[TW: Poo/Scat]

Hey there,
I am quite into Anal and Prostate play. The problem is that i quickly get the urge to poo if i penetrate myself with dildos.

I dont have any trouble with small prostate vibrators or fingers, but if i use a normal sized dildo or something bigger, i need to poo after a short amount of time.

I always clean with a anal shower before i go into anal play, but somehow my body manages to still find something.

I really enjoy the feeling of bigger things penetrating me, so i would love to explore that feeling more intensly without any trouble.

Does anybody have experiences or tips?