I think the best chance you have is when silver medallions get upgraded to comfort+ seats at T-24, and checking in right at that moment to see if any of those seats are an option.

I really wish Delta would not sell these fares. They can't be making that much money off of them and, at least from FT reports, they seem to cause a lot of confusion. I think they cause a lot of confusion precisely because most frequent travelers, who would know what they were getting themselves into, would never buy an E fare in the first place.