My coworkers were no more productive than me: IMNSHO, they would end up dragging as much busywork out of every problem as they could, simply because they were too overworked to think more than one step ahead.
To wit: we were running 10 AWS servers - to serve a mostly static website and handle a few hundred REST API calls each day.
Of course, if the client actually has to pay $200 per hour you're present, it's exceedingly likely that the overtime culture will stop overnight. It's obvious that it isn't working already, once the company actually pays for it as well, it is bound to stop.
The problem wasn't the long hours - it was that places that push long hours tend to get other, even more important things wrong as well, like product-market fit.
You could do taht with 2 instances and dropwizard (https://www.dropwizard.io/1.3.9/docs/)