This problem still exists as of May 2021. Autofield saved a lot of time, and i manually shortened the length of all of the string fields, and then the write to SQL went smoothly. Before that, though, it was a series of seemingly random errors, trying to write some fields, then other fields and getting non-specific error messages which didn't enlighten me OR solve the problem. The Thrill of Solving, indeed!
Thanks to the community for lightening the load, again. Alteryx is a big complicated tool that can do everything, and usually someone knows how to do anything you can think of, but connecting those facts to achieve a solution is often fairly magical. I really appreciate everyone sharing their expertise and experience. Thank you.