One thing you may want to do if you're route is that long. Run it in one direction one storm and then run it backwards the next. That way the same customers on the tail end of your route aren't having to wait so long each time. Of course, then all of them are waiting a long time sometimes, but it is something to consider.
I actually have 3 legs to my route, basically 3 different loops that I can combine into only 2 if I want to. I have some customers that get priority service each storm (my high end lawn care customers) and some that are always on the tail end (my low budget seniors), but I do reserve the order of the ones I run in between them.