Man, I don't think they could make it more difficult. As far as reaching the steep slope, I've used the invisible glass hand cleaner tool
But it only worked so-so. I've used microfiber cloths, paper towels, and the blue workshop towels. I've used Invisible Glass, ArmorAll... a variety of glass cleaners. No matter how I clean it I am ALWAYS left with streaks. The inside gets really bad when the chemicals from the dash cook off in the sun.
Anyone have a pro-tip on how best clean these steep slopes and what to use?