Yes, those are good. I do single leg presses pushing the plate with my toe rather than flat-footed. It's very important to track your knee directly over your foot, IOW angle them both just the same. The lower on the plate you put your foot, the greater the quad activation and the less the hamstring activation. Eccentric exercise works at least as well as concentric. The main thing is that the exercise be pain-free at the knee. My guess is that you can use more weight eccentrically and stay pain-free. In general, eccentric exercise causes more muscle strain than concentric and strain is what you want.