Hi Chris,
for experimenting and implementing, I guess a lower resolution than 8k would be preferable (I typically have to start FG 50 to 100 times to implement rendering stuff - so it matters a lot whether loading time is 20 seconds or 2 minutes...)
The processing should be like for the textures to get the same mapping, i.e. create normal map first, then do the border trick. As for re-sizing, I don't really know. You're probably altering the normals somewhat in the process, but resizing always leads to information loss, so I don't know whether it matters either way.
(Not really an expert in normal maps).
Perhaps let's try a simple re-size first.
(Still might be a few days - I've finished flight-testing the Shuttle today, but documentation is lacking...)