Mast vertical, stays taught, (no need to tweak them like a guitar string), when sailing in a normal breeze, 8-10, you should see just a little slack in the leeward stays. Nothing high tech. All the stays are 1/8", no Loos gauge needed.
Here are some photos from our Capri-18 days. I installed a Johnson quick release lever on the back stay. All I had to do was attach the forestay, and pull the lever on the Johnson quick release lever and the rigging was all pulled tight. So simple, even a caveman could've done it! The one photo shows her on a mooring during one of our sailing trips to Catalina Island.
One of the best sailing, WAY over built, unsinkable boat in her class.
WHAT A GREAT LITTLE BOAT
Don