@kronos& smad
I think the next release of WinUAE (0.8.22R2) should have full RDB support in it. I'm waiting for that myself to do a similar thing with my miggy's IDE disk. I've tried using FAT partitions in my Amiga but my machine is too darn slow and flakey :-(
I'm running Linux here, but I think my kernel is without AFFS (RedHat7.2). If I build myself a kernel with it in do you know if it will read my RDB disk? It'd save me waiting for WinUAE, and of course the pain or running Windows!