Nothing wrong with a guy paying his way through collage by cleaning a few windows, in fact it shows real initiative.
Stick a sign in a shop window offering free window cleaning in exchange for ladder storage.
Everyone loves a try er, if you explain what your doing, and why your doing it, someone nearby will let you leave it behind their shed or something.
You have been out canvassing, so can obviously talk to people.
If I were you, I would look out for someone working in their garden, it's better than knocking a door, explain your situation and ask if they know someone that could help.
I have seen sack trucks with inflatable wheels for £20, tie one end of your ladder to the upright with the handles,[tie low down near the platform] you can then pull your ladder behind you instead of carrying it.
Go for it mate, I would, and good luck to you.