So I picked up monoprices version of a powerbridge. I can easily seal up the electrical side as it uses a 1 gang box, and I could put a putty pad.
The issue is with the hdmi side of the bridge where the wire comes in. I don't think code would allow me to use a 2 gang box with the low voltage and electrical in the same box.
It appears that caulking the low voltage side won't work cause its a big hole for the hdmi cable to come through.
Great stuff expanding foam...