Build against Let's Encrypt's Staging Environment

I recently hit the rate limit trying to spin up a multi-site setup on the stable branch. I found some suggestions on the forum how to work around that. Though I also found that Let’s Encrypt just recommends to build against their Staging Environment (Staging Environment - Let's Encrypt). Could I do that by using a command flag or setting a different url?

There is no support for such configuration at the moment, as our launcher setup is tuned for standard installs.

You can edit the LE template manually on your checked out version to point to staging though.