Jerry,
I've never split a carve either, but that isn't stopping me from showing my ignorance!
I see no problem if your boards are wide enough to still have roller support at the well in the bottom piece.
If you have rails on each side of a 1X12 (usually about 11-1/4" wide in my experience) you should be good-to-go as far as I can tell.
I would just be concerned that the roller could drop at that point with just a 1X12 board.
Ken,
V-1, 2, & 3
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