Yes, making the drive active made no sense, I was getting desperate!
I have experimented with turning the cache off (using gpedit.msc in CMD), but found it a pain if you have large amounts of pics in a single folder, as each time the folder is opened the icons turn to thumbnails quite slowly, especially when the jpegs are in raw format, or large 4+mb size. With cache enabled, once it's initially loaded the data, it's quick (and would be even better reading data from ram).
The Ramdisk software has virtually no settings, but I think you're right, it does need the os to think it's a fixed drive. How would I go about fooling the system into thinking it is a fixed drive? More to the point, how does it know it's not a fixed drive (media type?)?