The question I have is, what are you wanting to do with these peaches?
If you are wanting to can/preserve/make jam from them, then you would need quantity. The quality will be at least as good and most likely better than any store bought ones you would find and even meet or beat most 'farmer's market' ones, these days.
If you are wanting fresh eating/exhibition peaches...go ahead and thin them some more 20% sounds about right.