I personally dont think a Loos guage is much use with boats other than one designs, who do rely on them. The first issue is I doubt Louise is going to find tension settings for a C27 anywhere. My CS36T comes with a three inch thick owners manual, including several pages on rig tuning, but no tension settings that I recall - per the instructions, just sail up wind and tune... The several times a yard set up our mast, no one carried one around.
If you have figured it out and it works for you, that's great, but hands on testing gives you a direct and accurate answer at no cost...maybe I'm getting to be an old fuddy-duddy... but that's a different thread.