Vacuum hose too short? Call your local friendly carpet cleaner with the 50' hose lengths.
Local carpet cleaner is a good idea, and probably also specializes in duct cleaning as well. Depending on how your ducts are laid out, you might be able to use a chimney brush.
I had a mouse build a nest using a roll of toilet paper in the fresh air duct of my pickup. Smell went away, but ever so often when I turn on the fan, little bits of toilet paper still come shooting out.