If you really want the trash "gone", the closest I've been able to manage was protecting it. In a terminal, type "chmod 0 ~/Applications/Data/Trash". If you try to delete something, it'll warn you that it couldn't copy the file. You have to delete with the shift key pressed, as Prometheus has mentioned, unfortunately, but at least you won't accidentally send things to the NAND anymore.
I created a sym-link from the trash to a directory on my SD card so taht any deleted files go there instead, but I almost never delete anything that way, I prefer command line interaction.