I think we both have Tayana 37's and I've used the folding rule method as a means of applying proper tension in all shroads and stays with the exception of the forestay which has a roller furling foil. Not sure how this would be measured other than assuming that the tension in the backstay can be correlated to that in the forestay.
Cutters require entirely different tensions for headstay/forestay ... both additive vs. backstay/runner tension .... Damn difficult to do with a single backstay !!!!!
On my Ty37 FOR UPWIND I tension my staysail @ less than 10% (sometimes entirely slack) so that most ALL the backstay tension goes into the headstay .... so that the 'luff hollow' of the GENOA matches the curve/sag of the headstay. Sometimes I just add to the backstay tension via runners ... depends if cruising or racing.
I use 'luff stripes' on the headsails so that I can easily visualize if I have the backstay, etc. tensions 'perfect'.
My typical Ty37 tension set up is: 15% caps, 18-20% fwd lowers, 10-12% aft lowers, 15% intermediates, 20-25% backstay (for upwind)/headstay, 10% forestay, and bobstay at 15%. I try to keep a 3/4" fwd. pre-bend in the mast at the spreaders to keep the mast from pumping without the need for running backstays. DownW or BeamW, I progressively tighten the forestay depending on the windstrength. If staysl with no topsail, then forestay goes to 15%++.
RichH Ty37 #423