There's a way of patching/booting tires that results in a permanent repair that usually goes the full life of the tire. Make a big boot (bead to bead and 1 1/2" past the cut n both directions) of sailcloth. Ask any sailmaker for a scrap of dacron sailcloth for say a racing dinghy like what would have been used 30 years ago. Glue it in with contractors' grade contact cement. (Sailcloth is designed for abuse very similar to what tire casings see. The repairs hold up just as well as the rest of the tire, or they do if you don't take the tire off too many times. If it starts to delaminate, just glue the boot back down with more contact cement.)

Ben