The bit that everyone likes to leave out about the 3 months at 40C retention standard is that it applies to drives at end of life, with all their rates write endurance used up. Drives that are not so worn-out have much longer retention—and a drive used only for cold storage of infrequent backups would hardly use any of its write endurance.

The recommendation to have the drive be powered up for two weeks after taking it out of cold storage is only so that the drive can do it's low-priority background checks of data integrity. If you do a full scrub of your data from the host system, you don't need to worry about that, because you'll be giving the drive all the same opportunities to discover bitrot.

None of the above changes the fact that SSDs are still quite expensive for cold storage purposes.