Placed the mast cheek blocks halfway between the spreader and masthead on mine. No problem with corralling the aft endi of the sail with the steep angle of the Jack Line from mast to boom. Used the design on the graph paper at this site. http://pearson35.com/projects/lazy_jacks.htm
Used 1/4" line, nylon cleats on the mast, brass rings in place of blocks, ans small cheek blocks on the mast. A halyard would occasionally hang up on the cheek blocks on the mast. Mounted two of the thee legged mast steps over the blocks, one on each side. That solved the hang up issue. The lazy jacks cost very little, the line and the cheek blocks were the biggest expense and has worked great. Really nice to just drop the sail when going into the harbor especially single handed and take care of flaking it after I'm tied up in the slip. The lazy jacks are stored against the mast except when actually used. It's super easy to pull them forward and hook them under the cleat when I get ready to leave the slip and deploy them just before dropping the main going back in. Really don't like lazy jacks that are permanently deployed especially if they are hung from the spreaders. Just too many lines flopping around that aren't needed till you drop the sail.