Boy, I'll bet I'm sounding like a real pain in the
Is it too late to add another layer (or two) to that baffle? Doesn't even have to be MDF, it can be cheapo OSB if you prefer. You just want to have as much mass on that baffle as possible, especially in this case with a large baffle, a "box" enclosure, and not exactly a whole of a lot of rigidity at the top. You definitely don't want enclosure resonances to show up once it's done. It's worth the extra work and a couple more bucks now.