It will be cheaper i think to get a SSD drive and put it in a USB box, a 256 Gb SSD is about 200 US dollars and add to that 20 buks for a box with usb 2.0 to house the SSD.
As durable as flash storage, should easy take 20 full revolutions when you roll your UTE in the outback
Maybe jookin will even bundle a SSD box to get ppl on the right large storage track.
just looked on ebay, 256gb sdxc card is like $800. memory is gonna cost more than the recorder if you go to big.