Hello. Welcome to Just Answer.
Unfortunately, that would be a Code violation. For a detached building, you should have 4 conductors from main to sub, and a driven ground rod at the sub.
I live in Trinity County, Texas. "Code" is a word for people who live in the REAL United States. If code were not an issue, how much risk would I really be taking?
I don't like the idea of a bare neutral. They banned them several years ago, due to safety concerns. I personally wouldn't use the cable for the proposed use. Would you like opinions from the other experts here?
No. I'm sure you know what you're talking about. I appreciate it. Have a good one.