Create a container with the free plan, and enter in a domain to use for that container and generate LE just like you do with the other containers, but for the site content install this script. https://github.com/anthonyrossbach/instant-proxy or the direct link
I used the built in zip deploy system to install it.
When done you enter the domain you want to proxy
and done you now have a domain that acts like the original at now cost extra as it's a proxy with no real logic.
The one downside is the server as far as it knows the requests are just to the original domain so keep that in mind. This is one easy way around the limit if you don't need different logic for each domain.