Your docker settings are stored on flash, and you can get them going again just as they were using the Previous Apps feature on the Apps page. But, you may not need to even do that much.
Since this is just a drive replacement, with shrinking the array, you might just do it the "standard" way, one disk at a time.
Replace parity first since it needs to be largest and let it rebuild.
Then proceed with replacing / rebuilding whichever disk needs replacing the most (SMART report), or whichever disk has the most contents.
Repeat until you have all the new disks in.
Then move the data from the remaining disks using unBALANCE plugin, Krusader, or whatever you prefer.
When those are empty, New Config without them and rebuild parity.
That method has the advantage of keeping your server going throughout the whole process. And you have parity protection through all of it except for the rebuilding parity steps, and that isn't much risk if you keep the original disks until finished.