Advice Please: installing more than one multisite network

I'm not sure if possible to install multiple multisites on the same domain; and if so, will domain mapping still work.

I'm looking to have some fairly complicated networks setup using the same domain name - with multiple languages.

so wondering if installing separate instances on subdirectories is viable.

example.com/en/
example.com/es/

example.com/en/customersite = customersite.com

the different language sites are going to be focused on different things so I didn't really want to simply translate them, and I need Admin to be in different languages.

thoughts?