Suspenders Under Sweater

I've been thinking about buying a pair of suspenders to wear underneath my sweaters, as I've been having trouble keeping my trousers up despite their being tailored/in my waist size (28). Where would be a good place to look? Should I be looking at specific material for the suspenders to protect my sweaters from snagging/chafing? I've found a couple options online, but they mostly used metal clips that I think would damage my trousers, which in fact come with suspender buttons.

As an aside, have any of you gentlemen ever found having a thin waist to be (at least) a minor annoyance? I'm by no means sickly, am of above average height and build, and swim often... Perhaps this is a problem that fixes itself with age?

Thank you for your input.