Having to currently dedicate a whole domain to run on DO DNS to be able to use Let's Encrypt on Load Balancers is very cumbersome. I have lot's of domains, I manage through my current provider's API. When hosting something on DO, I just point an A record to the right IP. For all ISP's I know, that's enough to be able to generate a LE certificate.
I asked this through support, and the only answer I got was " in order to use Lets Encrypt on LoadBalancer the domain must be using DigitalOcean NS". Thanks but I already knew that. It's however not a technical valid answer.
This requirement basically makes LE unusable and not an option for me.