Cutting Carvey dust port: top (plexiglass) or back (sheet metal)?

Title pretty much says it all. I am going to hook my massive (2500 CFM Clearvue MAX cyclone) dust collector onto my Carvey. Way, way overkill. I may end up just running our big shopvac instead. Anyway, point is, I want to cut a 4" hole in the Carvey enclosure. I’m thinking about either in the top clear plastic, or in the back towards the bottom, where it appears to be just sheet metal.

The top has its advantages: very easy to drill, no 90* angle to connect to ceiling mounted ducting. But it also will look kinda nasty, and will draw air/dust up past the motor. It also will have to move when I open the lid.

The back will be more hidden, and will draw air/dust away from the motor. I just need to make sure there’s nothing I’m going to be ‘hitting’ as I make the cut! It seems like its just metal, but I sure hope I’m right!

Just sheet metal underneath the panel and above the base (still metal down there, but you wouldn’t want to cut into the bottom as well). I’d be concerned about running the collection hose right underneath the PSU and the controller. You’d increase your chances of EMI, and if you mill anything conductive it will be pulled right by some exposed electronics. Obviously, you’d be voiding any warranties.
Have you measured air quality near the Carvey? I’m guessing (based on your dust collection unit) you have equipment that throws much more than the enclosed CNC.