Thanks for reading everyone.
In regards to a "budget" named Defender, I actually think I'd go Ion Cannon over Mangler, at least on Rexler. The control aspect is really useful, and potentially lets you set up some good attacks later. Consequently, I'd try really hard to get one in that squad you posted, Hungry FFG. Downgrade one Black Squadron to an Academy and you free up 3 points. That gives you and Ion Cannon and a great blocker to mess with enemy formations. TIE Fighters punch really hard up close for their points, and the Ion Cannon really supports getting your TIE Fighters at range 1. There's a strong argument to keep it as is, though.