For some reason the bends that worked so well with a square-tipped blank didn't bend the round-nosed ski nearly as much as I wanted so I've decided to go with grooves cut on the mitre saw. My original objection - aesthetics - is no longer a concern because once the skis are assembled I'll fill the mitred slots with putty. Once the skis are glassed, sanded, primed and painted there should be no hint of the slots.
I've heard that you can make thin slots with a hobby knife - the problem is that I have no way to control the depth of such cuts. The mitre saw is infinitely adjustable in that regard. And to my way of thinking there must be at least a small kerf to allow the skis to curve upwards.
Pressing the barely-bent ski flat again.
Two flat, if slightly water-stained, skis.
Clamping square to the bench edge to mark the slot locations.
Mitre slots marked. The saw blade kerf is 1/8", so I'm spacing the cuts 1/4" apart. Note the test piece for reference - those slots were not a measured distance apart.
I hit the skis with the heat gun for several minutes to remove moisture - I'll let them air out for a day or two before cutting the slots.