Somehow, I had forgotten entirely about the underscore, despite it being my go-to choice for a space substitute for many years.
(These days, with good Powershell and zsh configs, I don't even notice the spaces on the command line. Autocomplete escapes them for me.)
@cerebrate glad I could remind you! I use zsh as well. I usually create names without spaces at the command line, and names with spaces in a GUI. I tend not to have much crossover so it works for me.