I think it might be nice to have a "Supplemental Round" in the middle of the draft to accommodate those people who lost keepers to injury after the keepers were declared and want to throw them out. This wouldn't be too high to create a competitive advantage, but not too low either. If you keep five, maybe making it between the fourth and fifth rounds makes sense, or between the fifth and sixth rounds.
The issue may come up as to who would be eligible to be thrown back, though -- do you allow the Harvin and Crabtree owners to do so when they'll miss most of the year, but not all of the year? Or do you restrict it to players that get placed on Injured Reserve, as Maclin has been? Just something to keep in mind as you consider this idea for your league moving forward.