Use sub directories for an established site

I would like to move my existing WordPress install to Multisite but unfortunately I’ve run into the redirect loop issue. I’ve been reading through the codex and realize that since my install has been around for longer than a month it will force the sub domain network option. Is there a way around this? I’d really like to use the sub directory option and avoid changing my url during the install. Can I ignore the suggestion to change my url and keep the www in my url?

I came across the section below in the Multisite Network Admin notes but I’m confused as to how this would work into the process:

https://codex.www.ads-software.com/Multisite_Network_Administration#Switching_network_types