Maintenance Mode and custom content block

You have a really nice product! I’m so happy with it.

My question is related to the integration of my page with my uptime monitoring service. I’m using Upzilla.co for my server and website monitoring.
I don’t have any problems in regular page mode. My problem is related to Maintenance Mode. This service just isn’t able to detect this mode properly and I’ve asked the support of the Upzilla and they suggest adding some custom code block that could be defined in service settings to avoid any incorrect alerting.

Is it possible to add a custom code block for the maintenance mode?