I'm having the same issues on my house and if I stay there long enough, I plan to seal the crawlspace. In such case, I'd remove the old insulation, get some heavy plastic and come down the brick walls with it. Then cover the floor, sealing all plastic seams together. Add a dehumidifier, drain it outside, and call it a day.
With no ability to take in air, it isn't necessary to seal the floor beyond sealing against critters.
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