I always thought that something like "non-official" promotion system was on Voyager, crew members were "virtually" promoted, and crew got their real promotions when Voy arrived home
They already have something like that, it's called "field promotion". As seen in "Menage a Troi" and the BoBW two-parter, field promotion includes rank insignia.
Tom was demoted then restored. Harry had time in grade, was a department head, and a good record. Promote him.
It's a no brainer, right? Every previous ensign was bumped up in under three years except Ogawa, who took a little over three. Seven years was ludicrous.