The OP is essentially defining as a "rec kayak" any kayak that has no bulkheads or only one bulkhead. Logically, less-than-two-bulkheadedness can be a general feature of a rec kayak without defining the class of rec kayaks. Stated differently, kayaks other than rec kayaks can have less than two bulkheads.
For example, Mariner kayaks were usually sold without any bulkheads. The Broze brothers generally recommended against bulkheads and in favor of bags. Yet, I don't think anyone would call a 17' composite Mariner kayak costing $3000 a rec kayak.
So also canoes. Some canoes have built-in flotation tanks (a form of bulkead) and some don't. That feature does not in my lexicon define something as a "rec canoe". In fact, the most expensive racing canoes may be the hulls without flotation.
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