14 Mb IIgs?

I see that some of the IIgs emulators have a 14Mb option, and one of the ROM switcher cards has an option for a ROM that supports 14Mb of RAM.

However, my understanding is that, due to the way the address decoding circuitry is designed, the unmodified GS hardware can really only address 8Mb.

Has anyone done any hardware hacks that allow proper decoding of the full address space and 14 Mb of actual physical RAM, with the patched ROM?  I would assume that it would have to be some kind of CPU socket plugin thing.....