Mike..thought about this some more & looked up the Skinny 6 dimensions..wow..they are skinny. At 4.5 inches wide at the baffle, I'd see no issues with using a solid wood baffle. That's really narrow to be suffering from expansion/contraction & splitting issues.
You can calculate, or at least get a ballpark estimate of wood contraction/expansion by wood specie, with the Shrinkulator(link below)..using (unfinished)Sapele at 4.5 inches wide and a wood-moisture content change of 4%, it looks like 3-4 hundredths of a inch change in width..not much. http://www.woodbin.com/calcs/shrinkulator/
But..even if there was a more significant change in width with the seasons, there's a tried and true option that is sometimes used with table tops having breadboard ends. The narrow baffle width would allow this to work well I think. You can hard-attach (glue or, in your case, bolt) on the baffle centerline-only (not edges) and ignore any expansion issues. The center doesn't move(even in wide tabletops). With a hard centerline attachment the board is still allowed to expand and contract as it will with no ill effects. Given how narrow the baffle is, I think a centerline attachment in multiple places off the braces, would be plenty to hold the loaded baffle in place.
A couple ideas(rough sketches, but you'll get the idea):
The foam gasket could be something like this:https://www.amazon.com/Density-Adhesive-Weather-Stripping-Insulation/dp/B06XCK65QM
Check Ebay, Amazon, Thomas Registry(thomasnet.com), McMaster Catalog..there's a foam strip out there somewhere with the right dimensions. I'd make sure the strip is closed cell foam though. Open cell doesn't have much 'body' to it.