I would also say, try it. You certainly need a brim or raft.
Recently, I've made a print with free-standing walls of 0.8mm thickness (just flat walls, no edges, no bends). It worked.
You may have to keep vibrations in mind. They may affect the print quality higher up in the print. It's certainly an issue with an UM1, maybe less with an UM2 (due to the difference in stepper driving).
You can do it, but you really have to make sure it sticks well to the bed,
this was one of the first prints I did a few years ago
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