Can I mark a SD Card as permanent storage?
Yes! You can change the volume from a removable device to a fixed disk by flipping the removable bit. Lexar made an application for Windows called 'Lexar BootIt', a well known application for this task.

I found a solution involving DD, but I have not tested it and I'd severely recommend backing up your card before doing anything with DD/Terminal. I created these instructions quickly. If you aren't comfortable with Terminal, use Windows! I am not responsible if your SD card is permenantly damaged in this operation. dd is exceedingly dangerous!

Use diskutil list in a Terminal instance to list all volumes. I found my hard drive under /dev/disk1. Remember to substitute disk1 in the later commands with your own disk name.

Don't forget to unmount the disk:

hdiutil eject disk1


And now the command:

dd if=/dev/zero of=/dev/disk1 bs=1 count=1


Again, back up EVERYTHING before doing anything with dd!