Large Amount of DTED data

I have a large amount of .dt1 data that I've compiled each dt1 into a hillshade tiff, color tiff, and vrt file for elevation and display purposes.  The issue is that the file takes forever to load.  The program doesn't start even after letting it sit for more than 3 hours.    I have DTED covering the entire continent of North America.  I need this DTED to be in multiple individual layers, because the user should be able to cull a piece of the DTED away or remove it / replace it with new DTED data when necessary.

How can I load upwards of 800 dt1 files converted to tiffs into osgEarth?  Each file is ~2 MB in size.

Edit: I'm using osgEarth 2.10 and I've put all these files into the .earth file using a python script.  I can load the first ~100 tiffs no problem (especially after caching), but going over 100 causes the program to never start.  I realize it's not a layer issue though, because I can copy the layers that have been added in to a different map and it'll run fine (twice the layers).

Josiah,
This seems ambitious. The only advice I can offer is to set your min_level (on each layer) to some number higher than the default (which is zero). osgEarth is trying to build LOD 0 by compositing 800 layers -- and you probably don't need to see elevation data from orbit anyway. Try min_level="7" or something like that and see what happens.

Thanks Glenn,

Now it runs, but dted takes a long time to display (but it is showing a new tile every 20 seconds or so).  I think I'll just compile all the data into a single tif and load it that way without the ability to remove these chunks.

Is there anyway to set the min level and have it not display the data until it can display it all fully?  (a way to basically let osgearth do all its calculations on the data before displaying it at all).  

Right now, when I compile it all to a single tif, it shows pieces of it as I move around when the min_level is set to 7.  When I don't set the min_level, it takes a while to cache the data before starting, then starts with all the dted displaying properly.  I basically want the same effect, where the program waits to start until the dted data is fully cached, and then the map displays.

Sorry but no, there's no way to do that.