I have given up on trying to watch her feet at all, I now just watch her top line. If she is running the way I want, it will be perfectly flat all of the way through the board. This is guaranteed not jumping, and therefore what I want. When I see this I mark it and reward. When I see a lump in her top line (ie she jumped), I just do not mark it and either throw the toy but not very far, or I do not throw it at all. I think I should still be throwing it, since I do not want her to lose speed/motivation. Since I am still shaping behaviors away from the field, I feel like the click holds enough weight to let her know that that was not perfect.
I am LOVING running her through the U shaped tunnel then getting a head start. She comes out roaring fast and focused on the board. It also allows me to be ahead, which is very nice.