They don't exist as a file on the HD so therefore you can't just create one in a text editor and expect it to become the norm. The values are assigned when you CREATE the partition and are written directly to the HD's Rigid Disk Block, not stored on the HD as a file.
The 'buffmemtype' option doesn't exist for HD's, only for add-on's like ZIP drives, CD-ROM's, etc.
One possible solution is to find a copy of FastMemFirst (WB 1.3 - System folder), drop a copy in your C: folder and see if by loading it directly after the SETPATCH command it helps any.
A word of caution though ... It might crash the system as it's not written for the A1200, it might not - Can't test as I have no WB1.3 here.