Can you think of any major treaty in history that has NOT been negotiated in secret?

No. For the government to decide which local industries should be winners or losers without first consulting the public seems to me to be an abuse of its mandate.

If there is a legitimate economic case for why some industries should be the winners and other the losers, (and I do think that sometimes such a case does exist), then make it public and let the public support you.

Yes it will be harder to pass the treaty but that is the price we pay for an actual democracy.

And in the end it will not be any more efficient to hide the negotiations as then corruption becomes a major issue.