The key with baffles is to keep flow as slow as possible through them, so bubbles don't get swept through by the current. Wide channels equals slow flow. I'd probably make your baffles 2 inches apart, maybe 3 if you have the space. I'd do three baffles, widely spaced, rather than more, closer together. Your last baffle should be an under. Ending with an over doesn't do anything to prevent bubbles. I don't know how tricky it is to glue acrylic, but I'll let you know in a week or two. I'm building a skimmer. Seems pretty easy, and baffles are a good thing to practice on, because they don't really have to hold water. Since you'll have to have some gap to get teh acrylic into place, you'll probaly need to use weld-on 16, rather than the thinner stuff. You'll want to lay the sump on it's side, glue the baffles to the bottom side, let dry, then flip it over and glue the new bottom side, so you're always gluing flat.
Good luck. Hopefully others will have more experience to lend.
Nate
