Isaac Sorkin and Abigail Jones, apparently working under the direction of Lael Brainard, have prepared a very nice table on the candidates' trade positions for the Brookings Institution: Candidate Issue Index: Trade.
Sorkin and Jones have looked through voting records and statements to compile brief explanations of the candidates' positions on trade in general, NAFTC, China, FTAs, Doha, and trade adjustment assistance. Four Democrats and four Republicans are included.
Here's one of the pages as an example of the format (of course not every one is still in). If you click on the image the text is larger: