Okay, this is one of those took-longer-than-I-thought-it-would situations.
Figured I'd get the router table out, remove the fence, install the flush cutting bit with roller bearing on tip and run the hatch ribs thru. Turns out that the flush cutting bit that I have won't do a 3/4 inch thick board in one pass, cutter height is too short. Besides, with the router in the table, in order to have the bearing ride on the template and still have the cutter trim the edge of the board on the template side, the cutter shaft would barely be in the collet.
Okay, take the router out of the table and get a better grab on the cutter shank. Still, since there is a space between the edge of the cutter and the guide bearing, in order to have the cutter reach the face of the board against the template, the bearing was only riding on part of the 5 mm template. Worse, the difference between the shoulder of the cutter above the blade at the shank end, and the diameter of the bearing/cutter meant that the shoulder on the cutter rode on the extra meat of the rough cut, holding the bearing off of the template.
Also, with the head of the bolt holding the bearing to the cutter sticking out, it was not as simple as just laying the blank on a table with the template down and just running the router around the outside edge.
Had to clamp the blank to the edge of my makeshift table, supporting the free end with a makeshift prop and make several passes, fist with the bearing aligned low on the template, then again with it raised up a bit to follow the fresh cut. Back again for a fresh pass, then repeat.
Here you can see the template sitting on a few cardboard spacers to allow me to align it to the blank before the tape sticks. Also note the piece of 'no slip' mesh rubber carpet pad.

Here it is with the spacers pulled out and stuck.

And here you can see where the shoulder of the cutter left a burn mark and ledge where it was too short to do the job in a single pass.

Managed to sling plenty of chips (wear your safety glasses).

Here's a look at the cutter (blurry). Note the space between the cutter edge and the bearing race, and the gap between the face plate and shoulder at the cutter shank.

I started on the outside arc thinking that if I messed anything up it would be easier to hide up against the hatch skin. Was also worried about end grain chipping out at the corners of the tips. However, The Red Grandis is such nice wood that the router just ran along fairly easily with no problems on the end grain and only some minor fuzz that will easily go away with some sandpaper.
Here's the outside edge. The little dark 1/8 x 1/8" square is where the biscuit slot got exposed on the skin side.

And here's the finished rib once the template was popped off.

Tomorrow I plan to finish the other three ribs!