What about emulation mode?
Your /// can operate as-is in an emulation mode to make it think
it's a 48k Apple//+ (WAP has the emulation software: Disk 3EMM-01).
Titan made a ///+// card for the /// you might also be able to find -
it increased memory up to 128k in //+ emulation and offered a RAM
disk in native mode.
You might also be on the lookout at computer garage sales for the
"Titan ///+//e" - a set of two cards that turns your /// into a 128k
//e. You'll want to add a 65c802 CPU (in place of the 6502) to ensure
compatibility with newer Apple // programs (it has no effect on
native mode applications). The cards offer a RAM disk in native mode
as well. (WAP has a wonderful set of RAM drivers for these cards -