Your desire for both is your problem. You can't have it. If you want drive pooling, something must enforce you don't have two files on different drives with the same path. You have to give up manual control; you can no longer treat the physical drives as individual volumes because they aren't independent anymore.
The reason DFS wasn't working for you was because it is designed for distributed systems, to give the users a unified view and give sysadmins a geographically partitioned view. You had all the shares on one host..not distributed. To use DFS to fake what you want, install AD and HyperV on your server. Make one HyperV guest for each drive (use Server Core here). Put each guest into a different AD Site. Use DFS to merge them all. It's doable, but probably not worth it just to shoehorn Windows into a role for which it is not suited.