Is it possible to create a 'custom' Group Policy to limit user-access to "C:\"?

Question

I want to prevent myself from ever accidentally saving a file into some remote corner of the "C:"-Drive. I understand that Group Policies can be utilized to effects such as this. Would it please be possible to create a Group Policy that prevents all users from saving files to the "C:"-Drive? With the exception of C:\Users[user]\Desktop--it's fairly important that I still be able to save to Desktop.

My concern however would then be that the functionality of folders such as the following would be affected... :

C:\Users[user]\Pictures\Saved Pictures

C:\Users[user]\Videos

C:\Users[user]\Downloads

Would other apps still be able to use the "C:"-Drive as normal in this scenario? Would files downloaded from the web still be put automatically into *[...]\Downloads* etc. ? and would apps still be able to store their essential files into C:\Program Files (x86) etc., and would those apps still be able to access those files once stored there?

As for my own personal files, I have created a new partition to store them in; though, as I said, I'd like to keep using *[...]\Desktop* if possible.