I would just get a cheap off-the-shelf NAS that can do zfs, put the disks in raidz1. Copy stuff there, shut down and then move the box to your summer cottage or something.
Run the scrub every 6 months or so to detect if cosmic rays/bitshift/aliens is affecting the data in any way (zfs doesn't trust hardware, only checksums so it'll recover your bits).
Modern drives can and will take easily that 50 startups your're going to need for that 25 years archival time. If a drive fails to start, well that's why you bought the drives from different batches, had one spare on the side and were running raidz1.