With standup room I would be putting in a basment.. Or at least a door to drive my tractor into...I have a mostly stand up height crawlspace in my current house.
It has 6 - 8 mil sheet film laid on the dirt with 2 ft overlap at seams. The crawlspace vents are closed but not necessarily 100 % sealed.
I have a LG 40 pnt Dehumidifier set at 50% running down there. The air is clean and dry. The joists are clean and dry with no mold and look new(14 yr old house). Its a safe place to store metal items with no fear of corrosion or mold. Previous owner had it set up this way which I've continued.
I live in a fairly humid part of country, piedmont NC.
Sealing at least as good as mine with dehumidifier or better if you don't think my minimalist system will keep it dry is a good idea.