hi mate. It would only be used for the 3 pulling sides. I am thinking of buying them clips used for pulling tarps tight etc.have them maybe every few inches attached to metal or timber 4x2 maybe. the 2 clips at edge pull the cloth tight along the timber and the clips in center holding the cloth straight then pull down the timber under the slate and 2 clamps to hold while staple. It may seem a little crazy and most people would think. bye the time you set all that up it could have just been stapled. Might be time consuming to get it all right but could be quicker in the end and certainly easier. I was also thinking of some way of making a contraption to pull it easily all at once. While im here mate. Not sure if you familiar with Strachan 6811 napped cloth. It seems much stretchier side to side than length ways. How would you calculate pull index on this? Ive been going just under 40mm on all 3 rails as i really struggle to pull last stretch on short rail.