So your getting tear out on the router table with the back cutter in QSWO? Not much you can do really. Take light passes, no more than a 1/16" of depth per pass. Make your last pass even lighter. I wouldn't climb cut that one personally. Feather boards will hold the stock to the table, but they are designed to prevent KICKBACK, which is not the problem with climb cutting, its KICK FORWARD! There isn't much you can do that I can think of relative to grain orientation. You pick your best face for the show face, and now you are committed and can't change grain orientation. And chances are you will have some switch backs in WO that you can't avoid anyway. Given it is hidden in the groove, to the back, I would chamfer those rough spots to make assembly easier and move on. Do the best you can, and if it don't show, it ain't broke so don't fix it.

"Would a shaper do better?" I can say maybe, even likely, but no guarantee there either. I have definitely had tear out on the edges of panel tongues with both big panel raisers and back cutters on the shaper. It happens.

You might try setting the cutter to take its full depth of pass and shimming the fence out with a series of 1/8" hardboard shims, starting with three shims or so and removing one with each pass to go deeper into the edge of the stock. Sometimes this can help. Think of it as taking light passes, but advancing from a different direction.