Most Prospectors did not have a keel. That is part of what makes them appealing. Any keels would have been special order. Chestnut used standard "thin" keels and wide "shoe" keels.
I've read through old Chestnut catalogs and even posted links to one this past year, and they always had options for standard keels or shoe keels. Here is my post linking to a 1921 Chestnut catalog. See page 24 for the discussion of keel options.
Great find Robin! She sure is pretty! I think that the carrying yoke on this canoe makes perfect sense. I would be interested in something similar to replace my Chestnut Chum yoke.