Combine multiple uptime monitors into one SLA report/NRQL query?

I want to report on uptime for my application, but am finding the default SLA reports, and the NRQL capabilities, limiting. The issue is that uptime is described in this case by a success on all of multiple monitors, and downtime is described by a failure on any one of multiple monitors.

For instance, let’s say I have two monitors running, each once/minute. In a particular day, there may be a time when Monitor 1 and Monitor 2 both fail (e.g. the whole server is down), then a separate time when Monitor 2 fails but Monitor 1 passes (e.g. the “order” page loads but the “checkout” page is down). In this case, I would want to say that the site was down for 2 minutes total, 1 minute for each downtime instance, since I consider both the “order” and “checkout” page to be essential, and if either is down we can’t generate revenue.

However, I don’t see a way to do this. I could count the overall percentage of successes vs monitor checks, but that will essentially count the second instance as “half-failed.” On the other hand, I could take the percentage of successes vs monitor checks for each individual monitor and then multiply them together, but that would count the first instance as “double-failed.” I know how I would write this in SQL, but NRQL seems to be much more limited (e.g. only 2k rows can be returned from a subquery, no references to superquery tables inside subqueries), and I am not able to write the same in NRQL. Any tips or best practices for how to do this? Is this simply not possible?

I also have alert policies that combine monitors in this same way, so I thought maybe I could report on uptime through the alerts, but I didn’t see a way to do that either.