I've read through the threads and can't find anything on this...

I want to install grab handles but am hesitatant to punch through the vinyl.

For the stern, I want to mount them midway between the deck and the gunwale which requires running the mounting bolts through the vinyl then through the plywood which the vinyl is attached to.

For the bow, likely the same as the stern but the cushion attaches to fiberglass.

I fear that when I punch through the vinyl that over time the vinyl may stretch or tear from the mounting bolts back...

Any trick or is this something I should be worried about? The boat is stored indoors and is always covered.

Use a bezel designed for the grab handle and use large washers and nyloc nuts on the backside.

when I have to cut through vinyl, If you have room you can staple a small circle, And then drill your hole in the middle of the staples. And as was said, Use a grommet washer under the handle. GOOD LUCK