I would buy a gauge Pat. I know. They're expensive, but they really take all the guess work out of tensioning the stays. Maybe you can go halves in buying a gauge, with someone you know. If you belong to a yacht club, maybe you can all chip in and buy one and use it when you need it. I have an 86 O'Day 222 with a Johnson Handy-Lock on my back stay. When I need to take my mast down, I just loosen the Handy-lock, or tighten it after I get my mast up. I never have a need to bother with the adjustment on any of my turnbuckles. My friends have used my Loos Gauge over the years more than I have. I just keep it on my boat in case I, or they, need it. If you were to call and ask Rudy at D & R Marine about your stay adjustment, I really don't think he could tell you anything more than, "Just get it hand tight and make sure that the mast is straight." What I like about the Loos Gauge is that you pick a certain number in a range that corresponds to the thickness of your stays, which should be 1/8", and tighten the uppers to that number. Then tighten your lowers to a little less tension. The mast will be straight if you use the same numbers. I would pick the lowest number in the range given for your stay thickness.
Joe