No, you're thinking about this all wrong. What you're proposing are base workouts for building fitness long term. What you need now are short-term fixes for the end of your season.
That means big, 5K-specific workouts followed by good recovery, a significant taper so you're sharp but well rested, and then go for broke at league champs.
What follows are probably BAD IDEAS and I'm not recommending them. But big, 5K-specific stimulus for you right now are things like 3+ mile repeats at goal pace. If you're already racing once a week, you probably don't need a 5K-specific workout more often. But you can add to the stimulus by doing, say, 800 at goal pace shortly after the race.
Also, how well do you know the league finals course? Having the course memorized can be helpful. It lets you formulate a more precise race plan and avoid some of the mental effort on race day. If it's not your home course, sneak over there on a weekend and run some race-pace intervals on the course. Find the shortest lines. Practice the pace changes dictated by hills. Plan your start and your finishing kick. Think about what splits you might hit for an even effort.
A lot also depends on timing that's out of your hands right now. It's been a long season, and you need your rival to plateau or go stale right about now. If he hits a big peak instead, sorry, you did the best you could.