I can't try it, because I have more than enough nitrogen in all my tanks without dosing any. That's the problem with any all-in-one mix.
One suggestion. You acknowledge that extra K+ will probably be needed. But more K2SO4 probably won't dissolve. So why not add the same amount of Mg from magnesium sulfate (Epsom salts)? That will reduce the NO3 content, which can be made up for with KNO3; increasing the overall K content.