I suffered this issue for about 10 years! I've only every used laptops with my brain as a laptop has always been an appendage for me. For most of the last decade I've kept my brain and most of the files on a local disk on the laptop and then had an external HDD with additional data as External Files linked from the brain. Since that was an encrypted drive, it was always possible to define the drive letter.
Currently i'm using the super versatile Thinkpad Yoga 12 with a 512GB m.2 SSD as c: drive and an encrypted 2TB Samsung 850 Pro SSD just dedicated to my megabrain (currently 1.6TB on the disk). This configuration solved mulitiple issues. Now my megabrain is fully integrated onto one disk (with four separate identical backups in different locations), and the use of an SSD with highest spec Broadwell i7 processor totally eliminated the lags and hangs which had dogged my megabrain for years. One could draw a conclusion that the platter speed of HDDs wasn't quite up to the read needs of TheBrain, especially when activated heavily linked thoughts. I think sibleyd's point is that the problem you have has a very robust solution already. If you have all the files in the same drive, then there is no more drive letter issue, correct. I have all my files always moved internally to TheBrain and don't have external file directories to worry about on my local drive. (But don't get me started on the issue of shared drives... oh, already started on another post). Jim
TB8022 32bit Java 32bit Version 8 Update 141 Testing 22.214.171.124 Firefox, Office 2013 Pro Plus 32bit 64bit Win10Pro 64bit Primary Laptop, 8GB RAM, Intel Core i7 64bit Secondary Laptop, 64GB RAM, Intel Xeon E3 Brain user since 1997