Thanks so much for confirming that it is doable. And how challenging it is. I believe I have all the pieces I need unless one of the brackets that hold the flap are broken (either now or break during the replacement). Since the driving season in CT is just starting, I may hold off until late fall unless there are likely to be a couple of rainy days I can commit to having the car tied up.
Did you use a special tool or wrench to reach the nut holding the bracket? Can it be just loosened to rotate the bracket out of the way and then back onto the flap pivot and then tightened?