So, now you've got about 40mm of the end of a catheter sticking into your bladder (15mm of inflated balloon plus the 25mm extra). Your bladder amounts to a somewhat conical organ, where the upper part collapses on top of the lower part, and this catheter is poking straight up into the middle. The vast majority of the time, it just pushes the catheter over to the side as it collapses. Except when it doesn't - bladder perforation is a rare, but life-threatening, complication of catheterization. Assuming that doesn't happen, your bladder is mostly collapsed except for the urine trapped below the level of the holes, which is probably of no real consequence. Your bladder wall gets pushed against the eyelets of the catheter, and can basically get squeezed slightly into the holes. As you move and the catheter works in and out slightly, you're at risk for scraping off small areas of the bladder lining.
If you do this, please be prepared to seek medical attention if you find blood oozing out with the urine, and get emergency treatment if you develop a fever or severe abdominal pain. If you don't have the keys with you, be prepared for them to bring in somebody to cut the chastity device off of you. Embarrassing, perhaps, but generally preferable to dying.
These scenarios probably won't happen, but it would be foolish to go into this without knowing what the risks are.
I'm not intending to be critical. It's your body, after all, and you don't need my permission to do what you like with it. I simply feel it's important to make informed choices in what is potentially a high-risk activity, so I want to point out some of the potential downsides.