If you get good ports you don't need to worry about stabilizing them and so on. Of course PVC pipe isn't going to work wonders, but it can . Just screw that thing to the box lol, doesn't look too good in neato installs. Also there was something in my mind that has to do with the "roundness" of the mouth of the port, sharp angled ones didn't work too well for my friend Seahag on here. I didn't get too much in depth about that.
If you look at these ports, they just need a hole in the box and you drop them in.They don't seem to be leaking either if you test and fit them properly and add some carpet on top so it's even more tight.
I only wonder why are they only doing them in 9 and 12 inches in length.

If anyone finds ports of various length of that type please let me know .