There are plenty of professional canvassing companies who will travel wherever you want them. They tend to charge on a multiple of the value of work they book for you.
Do a search for 'doorknockers/roundbuilders/rounddevelopers etc, there's plenty of threads on here about them.
Personally I prefer to do my own canvassing, I tried one of them but they don't have the same commitment, so they book all sorts of silly jobs at silly prices just to get the figures.