I always left the grey tank open until just before ready to dump and would dump the black tank at the beginning of a weekend letting everything break up during the week. Most people leave their slides out all season. We would lower both sides of the awning and strap it down and that was fine, kept things dry but depending where you are and what type of awning you have, closing might be better. We also had lights on the awning and did not want to take them down every week.
Sorry you did not like towing, it is one of my favorite things about camping.
