-Other than leaving the company, what else would you suggest that I do to make upper level management see the insanity of having 1:1 manager to developer ratio?
Become an expert in your department in change management. This sounds like the biggest thing holding your teams back, just from what you've described. Mind your p's and q's with change management, adopt it at the core level and push for it as hard as you can without stepping on toes and I think you'll see that ratio start to widen.