If he has dementia it will be an exercise in futility. He will remove it. I see it more of a long term problem than help. Can cause ulcers and or necrosis of the penis. Use adult briefs with inserted incontinent pads . Put his pants/shorts over the brief backward. If he has no dementia place pants on correctly.
i considered that for my husband. He’s prone to infections and a nurse told me that since nothing is actually inserted, the chances of infection and necrosis ( an actual disintegration of the skin at the head of the penis) isn’t as much of a problem. My husband doesn’t have dementia but is so incontinent i affectionately refer to him as “Mr. Niagara Falls”. The nurse suggested a “Supra pubic catheter” that is surgically implanted right above the pubic bone into the bladder. She said this causes many less issues than a regular catheter. Do you think your husband would rip it out? If you don’t think so this may be an option.