Want to use multi-domains for large sub-directory multi-site

I have a new client that is a franchise with over 700 locations world wide. Currently, they have over 45 different multi-site installs on their server, which we are now responsible for managing. Aside from the bad coding practices we inherited from the last developer, I would like to see this all as one network so that when we push a new feature, we don't have to reply it 45+ times.

The issue is the are all different domains. i.e. http://www.example.com and http://www.example.fr. Each new domain is for a different country, some of which have laws requiring the use of their countries domains (so I'm told), and can not and will not entertain the idea of combining all into one domain as in the .com.

They also have all been set up as sub-folder multi-sites and they've been running this for far too long to consider changing that either.

So, the plugin you have https://premium.wpmudev.org/project/multi-domains/ seemed at first glance like it would do the trick until I saw the disclaimer in the usage tab about it not working well for sub-folder installs.

Can anyone here elaborate on this for me at all? I'd really love to be able to use this to solve the issue here, but I do need a rock solid implementation because of the demands of the client and number of sites they have.

Thanks,
Micha