As far as I remember from Wii days, you can plug the drive into a PC and tell the firmware to not go into sleepmode by changing a flag... you -may- be able to dig up and ancient guide about it I wrote years ago. That being said, just get a USB stick and be done with it. They are dirt cheap for huge sizes and won't give you any spindown issues... OR you can wait a few weeks until the SD adapter is refined and just stick a huge SD card inside and be done with external stuff forever
Im already using a flash drive thats the best option, you're right.