StableBit DrivePool doesn't actually use drive letter for accessing the pool.
They are there because Windows auto-assigns them, and for your convenience.
As for accessing the data on the drives, you don't need drive letters.
While most programs basically do, you can also mount the disks to folder paths. This would eliminate the need for drive letters and keep the disks accessible. And you'd access the data from something like "C:\Drives\Drive X" or "C:\Drives\Enclosure 1\TV"
So by mounting the drives to folder paths, you could have as many drives as you can connect (the upper limit I've seen is 256 drives) and have access to all of them. But you'd have a rather cluttered directory structure to navigate.
