Have you thought of ejaculating before you stretch ? Just an idea that helps me if I stretch in the mornings. Rather than have to deal with 'morning wood' I simply masturbate before stretching . It also feels like I get a better stretch in the tissues this way.
I have done allot of erect stretching with some success. I know this is not your inquiry but I wanted to say that you are not completely wasting your time. I think flaccid stretching is very important to so you may want to follow Still's advice.