I would think the Joplin vicinity Craigslists, out a hours drive in any direction, would turn up a suitable used canoe in short order. You may need to look often and contact quickly, but there are surely suitable used canoes available.
A couple of canoes that often appear used. And for good reason. And just NOPE the hell away from:
Pretty much any Coleman or Pelican, or any Mad River molded poly Adventure canoes. Yes, there is a reason there are so many for sale little used.
One higher quality, fairly ubiquitous used canoe that would probably work, a Royalex Mad River Explorer.
Scroll down to the Royalex Explorer on catalog page 9:
https://www.madrivercanoe.com/us/sit...%20Catalog.pdf
Yoke, no thwarts, gobs of lengthwise cooler room, and a decent all around hull. That can be paddled backward from the bow seat solo. Or Poled.
There are many other decent tandem designs, in Royalex and (heavier) poly and (lighter) composite materials. Rental canoes may be poly, and if you have a strong back there is nothing wrong with a well designed poly boat as a first canoe.
One good start for basic canoe design and material would be to pick up a Wenonah catalog. Yeah, their info is slanted towards their designs, but the front of the catalog is still a wonderful canoe primer.