I think the typical goal with weighted water carries is to eventually exceed the total gain of your goal event.
However… 5,000m is a lot on its own. 5,000m of ME training with excess weight would be a ton. In order to play on the safe side, it may make more sense to progress your ME training by breaking up the total gain over consecutive days.
That’s just my first guess, so I’ll ping Scott J. and ask him to weigh in.