I understand about fuel 'treatments' but forgive me if I place little faith in them. In my opinion it is simply better to have good fresh fuel than to trust some treatment to last some number of years.
Well, if you have the budget for new fuel every few months, great. If the treatments are good enough for TVA they're good enough for me and my little generators and truck engines.
In a perfect world, fresh fuel whenever you need it is a wonderful thing. However, the whole purpose of having a backup generator is to be able to use it during less than perfect times. To have a generator and not maintain a reasonable amount of diesel fuel storage is certainly not the wisest course. Additives and careful storage really do work.