Not a chance ... they are very rot-prone.

And St. Louis is too cold in the winter for long periods.

Bummer.

Any ideas on the most desert like plant I can expect to try in St. Louis?

Agree on the joshua tree. They rot here in Albuquerque even sometimes. No chance in MO.

You should try yucca schotti (available at Yucca-Do nursery).

Yucca baccatta may make it. High country gardens (not my favorite vendor) has Mora, county NM ecotypes that see temps colder than St. Louis and may seen even more snow. The Moreno valley is the coldest in NM - they saw -40 twice 2 years back further up in Angel Fire. Angel Fire, NM nearby was the coldest place in the nation a couple of weeks ago (in June!). They also have some cacti from Taos, NM that may make it.

There are native MO yuccas and cacti. Do a web search. You have some right in your backyard! They can probably take your wet if you duplicate their MO environment.

Opuntia imbracatta also may be worth a shot. Find CO seed or plants.

Good luck.

Yucca recurvifolia and Y. filamentosa would likely grow well in St. Louis. They can take cold and more water than most Western species. The key in your area is sandy soil or sandy loam. Try Plant Delights nursery online -- they are in Raleigh, NC which is zone 7B. You may find these two species in big box stores in your araea as well. Yucca Do Nursery (also online) in South TX is also a good source. Raised beds with good draining soil is key for your area. Yucca Do has some suggestions along those lines. Good luck.