Very simple backup app wanted

[glenthompson]

Maybe slightly off topic, but if this data is so important maybe you should consider an off site backup such as Backblaze? God forbid you have a robbery, fire or similar that destroys your laptop and the backup in the same room, an off site backup is safe. With only 4GB to backup this sounds like an option.

Along similar lines, does anyone know if I can run multiple time machines? I could keep one at home and run one in a JetDrive Lite on the MBP.

Do you mean multiple time machine destinations? In that case yes. Just go into time machine preferences and add a drive to use with it. In my case I have time machine backing up to 3 destinations. If a particular device is not available, time machine skips the backup,to that device.

I agree with your assessment that the OP needs an off site solution. With the amount of data, an online solution is ideal.