Swimming does erode my weartime by a couple of days or so (I usually get 6 - 7 days weartime) but I consider that a small penalty for the ability to be able to able to swim at my leisure.
I wear my bag not straight down like a lot of people do, but at a 45 degree angle towards my groin. That way I can contain it all in my undies (I hear of horror stories where bags have slid to the ground as they've fallen off, but mine can't because it's all contained in my underwear and the elastic would stop it. Besides which, it's never ever become totally unstuck in 36 years and I find it hard to understand how it does, unless it's not supported within underwear and just hangs down and the weight as it's filling pulls it off??????) and it's at a convenient lean to empty between my legs when I sit on the loo
Cloothing doesn't impede mine because my stoma is located a couple of inches to the right and a couple of inches below my belly button. I just wear high waisted jeans and 'granny pants' to accomodate it. It doesn't interfere with my beltline. I used to wear the tightest jeans possible (in my slimmer days) and all I had to do was empty a bit more. Then and now, I prefer longer tops which flow over my belly and give me a bit more emptying room