There are two areas that look like they need strengthening on that design. The bed plate needs support otherwise it'll bounce and flex like nobody's business and you'll get a crap finish. Can you not just use the profile as the base and put profile laterally across under the bed plate to stiffen, seems like there's an awful lot of empty height under the bed plate?

The Y axis plate also looks like it needs a length of profile or two behind it otherwise it might also flex when cutting in the middle of it.

Hope this post doesn't sound negative, just a couple of observations :)