Managing Dynamic Global Navigation with Many Subsites

Hi all - hoping there's a simple solution here I'm just overlooking...

I have a SP2010 site collection with a lot of subsites (2,000+). I've created one subsite here with multiple nested subsites for the purpose of multi-tiered global navigation, and want to displayonly this subsite (and its subsites) in my global navigation (along with some static navigation links and headings).

The challenge is that when I click the "Show subsites" checkbox in my Global Navigation settings, only ~50 dynamic items appear in the Navigation Editing and Sorting section. I've hidden all 50 of those, but I can't get to the remaining 2,000+ to hide them as well. Is there a way to do this through another method, ideally in batch? Here are some of the constraints I'm working with, and things I've tried so far:

1. I tried sorting the pages in every different way possible but it only returns the same ~50 each time.
2. I increased the maximum number of dynamic items to show within this level of navigation to 1,000, and it still only returns the same ~50.
3. I tried manually adding the global navigation sections and links that I want here, however it only allows a heading and one tier of links underneath it - it does not support the flyouts we've developed to show subsites of subsites of subsites (at its deepest it goes 4 tiers, including the heading). The method I'm trying here works on other site collections, and would work here if I could hide the other pages so that my dynamic menu actually appears in the navigation.
   
4. I can't do anything about the number of subsites on this collection. It was built this way before I inherited it, it's a highly-trafficked core business tool, and I'm pushing for an alternative tool to handle this process. But for today it is what it is, and I need to work around it.

Thanks in advance for any help you can offer up!