[Canadian Man]

Yea Chad I think you would be fine. As sean said I don't believe there would be much pressure in the filter anyway. Depending on the type of cannister the only pressurized area(after pump impeller) would be just a small area and the return hose to the tank.

As you mentioned they are availiable for heaters. It's amazing what a compression type fitting and or an oring will hold as far as pressure is concerned. I remember seeing a probe holder once that goes onto your return plumbing on your tank. Another item that's along the same idea.

I'm excited to see this mystery project!