Awlgrip seems an odd choice of for this application, but maybe you've
got a can or two left over from a "hullsides" project...?

I've always considered 2 part polyurethanes (like Awlgrip) to be part
of a 'system' that includes an epoxy based primer that all 2 part LPU
manufacturers provide. This primer acts as a tie coat between the
gelcoat and the LPU. I'm fairly confident that without this primer,
you'll not be happy with the results.

For interior applications, I'd think that a one-part polyurethane,
like Interlux Brightside or Pettit Easypoxy would be the way to go.

In this case, I think your "dewax and scuff" proposal would be fine.

MW
Los Angeles