Hey there Caelanbro.
Wouldn't it be better if you can move your User Folders to drive D:, instead of trying to switch the drive letters? I assume that's what you mean, so that you could save up the SSD's storage space for OS updates, System Restore points etc. Take a look at this article: http://www.pcworld.com/article/2110095/the-ultimate-guide-to-proper-ssd-management.html. It has a lot useful tips on how to manage an SSD as well as a guide on how to move your User Folders to your HDD.
Hope that helps. Let me know how everything goes.
Boogieman_WD