It might help to reinforce the tarp itself also.
Sailmakers use a material they call sticky back. It is a heavier gauge material (typically Dacron) designed to peel and stick down on stress areas. Another term to mention is spreader patch material. Once it is stuck in place it will not come loose.
Using that material stuck to the underside of a cover in all areas of expected stress should greatly increase the service life of your cover. It would be best to apply it before any damage, but it will work for repairs also.
The material is readily available from local sailmakers or on-line.
Insignia Adhesive Backed Black 54"