Is there a better option than "darts" to hold an upholstered panel tightly and still allow removal?

[brutal]

The dart has to be placed through the panel and beneath the upholstery, then pressed on the body panel. Pretty much the same as a door panel.

However, I'm looking for something with better retention as it's the back edge of a boat sundeck cushion. Is there any kind of two piece that locks together somehow?

Any ideas?

I may resort to a channel to hook the edge/lip the panel edge attaches to, then clips around the underside to hold that, but would rather not put holes in the deck cover.