|Before redownloading stuff, but still.|
So I found a couple of up to date GamesRadar articles detailing drive recommendations and a detailed how to and did the deed. The trickiest part was making sure the external HD I used for a full backup was formatted correctly (exFAT, Master Boot Record) so that the PS4 would recognize it. But once I cleared that hurdle, it was simple to swap the drives, install system software downloaded on the PC and dropped onto a flash drive, and restore the PS4 from the backup. The drive was 90 bucks off Amazon, so not too bad.
Now all I need is a sale on Uncharted 4 digital.