If you do eliminate it from file storage action, I'd probably set the whole thing up as swap.

One option available is to format your SD card with a UNIX FS (probably ext3) and mount it over your home directory. Very much a handle with care operation, but doable. That or just boot from SD, where there are extant tutorials, howtos, and toolkits. With either of these, you can leave the internal accessible with VFAT for Windows access over USB cable. (Or do like me and use ext3 on mmcblk0p1 with ext2-ifs in Windows.)