Thomas: 
There have been numerous notes on this subject.  Search the website for others.  I also have a 172K with a fixed window.  As I do some photography this is a pain.  There is a STC to change this but I believe by the time you pay for the STC, purchase the parts and do the work you are going to spend up to $5,000.  This does not make economic sense.  Better to look for another plane.  Now I noticed this week Great Lakes Plastics has an STC for a replacement window with a camera port in it.  It probably could be installed for less than a thousand dollars.