Okay - that's the procedure I used to use. Cannot remember how long ago now - seems to me to be a very long time I guess. But it's been since I developed the SLS and refined it.
See my post to AS for my procedure now. I guess my Physics and Mathematics background makes me automatically start measuring things and examining the geometry which naturally led to my SLS procedure.
My personal preference is to use a ridge line. For me it makes everything much easier since I can hang the suspension (with ridge line) with no weight except the approximately 3 oz of the suspension. Once I have that, I can stand in the middle and know if the ridge line is too high or low or just right. If not just right I can move huggers accordingly and with no weight on them, which makes that job very easy. That's all the adjustment I really need since in setting up the suspension, I automatically have the correct sag - that's guaranteed even before tha hammock is attached. Hanging the hammock on the suspension toggles is even easier, no adjusting, just hang the loops on the suspension toggles and insert the spreader bars.
Yeah - I've been using a ridge line for tarps for years now. NOTE: the JRB 11x10 tarp has a tab on the ridge in the center. Attach that tab to the ridge line and it will keep the center of your tarp high. I just use a micro carabiner and snap it in place. I run my tarp ridge line above the tarp though, instead of under it.