That might work as a temporary replacement, but I doubt you will get any long-term use out of it.
The OEM inserts in your cover were cut by professionals, and they also had a taper built in. They were wrapped and the seams sealed - all very hard for most DIY to duplicate.
I tossed about two dozen inserts when we closed our shop last year - you may find a dealer who has what you need in a dark corner of their warehouse.
But my best recommendation is a new cover. The vinyl may be beat by the sun more than it looks.
HTH
