I use the following:

  $ cat passgen.sh                                                           
  #!/bin/sh
  export LC_ALL=C
  printf "%.16s\n" "$(/usr/bin/openssl rand -base64 32 | /usr/bin/tr -d 'lIOSBGZ')"

This way if it looks like a number then it is. I don't usually mess up q/g and u/v with my fonts but its easy enough to ban more characters.

O / D can also be an issue with some fonts.