Another option -- check out the very low profile USB thumbdrives (the one I've got sticks out about 4mm or so). Or see if you can get motherboards with an internal USB or SD socket. Maybe combine this with PXE boot for initial setup (the pod gets built with a blank internal thumbdrive, and on first boot it installs the Linux kernel and initial ramdisk image on the thumbdrive). Edit: It looks like the motherboard you use does have a USB header on the motherboard, where you can plug in a boot thumbdrive.