I am not really sure how much your need.
Over the holidays I had my 5.3x13 tarp fill up with about 5 gallons of water and it had sagged down into my hammock. Stakes were all pulled etc.
No reinforcing. I just had 3/4" grosgrain loops made side by side, IE 1.5" wide and was going to reinforce them later, but wanted to test it first.
Well it did not rip or pull out but did stretch the sew holes a bit.
Next one I am building is a cat tarp and on that one I am going to do it like wilderness logics does their tadpole. It will have no tie outs. If I do tie outs eventually I will do a patch.