When I finally got to use the device I discovered the USB Hub overheating issue.

Even though I put ventilation grills on the back cover, the components are just so dense inside and the back of the RPi effectively shields its CPU (underneath) from any air movement, so it get hot in there pretty quick.

I drilled some extra holes in the back case, some where the fan will go and a few more on the vertical face to allow air to. come out the side. I glued on some supporting screw holes to secure the fan to.