I wound up using these parameters in a batch file for cgminer 3.1.1:
cgminer-nogpu.exe --icarus-options 115200:1:1 --icarus-timing 3.0=100 -S \\.\COM3 -S \\.\COM4 -S \\.\COM5 -S \\.\COM6 -S \\.\COM7 -S \\.\COM8 -S \\.\COM9 -S \\.\COM11 -S \\.\COM12 -S \\.\COM13
and it was finally able to recognize all 10 of these miners.
They're hashing along nicely around 334 Mh/s each.