So I ended up deciding to go with a traditional sight glass instead of a pressure gauge as I was originally thinking about doing. I couldn't find a readily available source of clear rigid tubing, so as a temporary solution, so I can brew this weekend, I stuck a length of copper tubing down a piece of flexible tubing and attached that to a barb fitting which is attached to a 90 degree elbow. It isn't pretty but it works and will hold me over until I get something more permanent.