I think you are right.
You could get a pair of those drill less roof racks that go on top and the either build a rail for the bed or try to find a trailer hitch post that is tall enough. It might be easier to pull a trailer.
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I plan on carry a 16’ touring kayak and will build my own hitch extender, but just go to Amazon or Harbor Freight or the your website of choice and type in roof rack or hitch mounted bed extender and there you go.