I'm yet to see these rust issue's in my GS 150 it is a 2016 and only rear grab rail / carrier rack, side stand and main stand have started showing some signs of rust rest it's still pretty much clean.
If you really want to keep this bike for long time then i guess permanent solution would be to clean these part's really good and then get them powder coated (kind of a permanent solution).
A relative of mine got his bike's complete frame and some other part's powder coated for 6-7k RS.