If your convinced its PVC, i believe most inflatable (Sturdy) swimming pools liners are made out of PVC, have a look around your local "leisure accessory" dealer that would specialise in Sauna's whirlpools, swimming pools, and look if you can get a repair kit, most likely the patches will be in blue, from the big 10ft diameter pools. They are about 2-3MM thick. I think that is the best alternative, as they sit in the sunlight anyway...
Have fun!
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