jch wrote:What if I used external hard drives instead and just rotated those off-site??
That would work just fine.
Does QRecall support multiple backup sets (one per external drive)?
QRecall doesn't care how many archives you have or how you organize them.
If you did this I would suggest creating two sets of capture and maintenance actions, one for each archive (let's call them A and B). In each action, add the "Ignore If No Archive" condition. When the drive with A is plugged in, all of the A actions will run and the B actions will be ignored. When you remove A and replace it with B the opposite will happen.
Remember not to leave a hard drive sitting unused for too long. The surface of a hard disk is (literally) fluid and is not designed for extended storage without being turned on. As long as each drive gets spun up and used at least once a month, you should be OK.