Is this not what you are looking for? From the man page of env(1)

> The -S option allows specifing [sic] multiple parameters in a script.

> [...]

> Without the '-S' parameter the script will likely fail with:

> . . . /usr/bin/env: 'perl -w -T': No such file or directory

I actually ran into this problem last week and just used the absolute path with an argument (/usr/bin/python3 -u) instead of passing an argument to env, and I added a TODO comment to figure out how to do this better. Now you made me find the right way :)