I'd think that bedliner spray might be a bit on the heavy side, but maybe it's because they spray it on thick...

Why not just apply the two-part coating on as usual, and dust with sugar crystals before it sets? Then you can wash off the sugar after it's dry (the sugar dissolves, leaving the rough surface) for the non-skid??

Surf board builders call it "sugar deck"

A courser finish could be had using Kosher salt or unrefined sugar ("sugar in the raw")