If you are not using the rear expansion port for an Individivision mk2, then personally I would use a CF card adapter and the backplate from amigkit. Although not hot pluggable, it makes it really easy to setup on Winuae and then fit the card without opening the case.
CF cards are easy to make images of on the PC as backups as well.
I run my DVI out of there so have had to cut the case to fit the CF card adapter.
I also use a wired ethernet card and transfer files that way.