Tiny house transfer--- critter/elements protection?

I built a shell for a tiny house on the back of a truck, drove it across the country and now I'm setting it down on the ground. I've poured concrete piers below the frost line and anchored some metal beams for it to sit on. I have a crane scheduled to move it from truck to beams, with a (very) limited window in which to address the underside of the structure... Hoping to get suggestions on the following:

-What do folks recommend insulating the floor with? It's a 2x4 frame with plywood sub-flooring, completely open on the underside

-What treatments will protect the wood from moisture/rot, pests, animals, etc? Ideally, something that can be applied quickly, also ideally with minimal toxicity.

Any advice is appreciated!

Thanks,
Matthew

P.S. to see photos from the initial build and trip go to www.thereverseoregontrail.com

I would have used treated timber at the start.
Can you get sheet polystyrene to insulate the floor. or wool bats trapped in a frame?

Ideally, staple insulation batts in the joist bays and then cover with insulation board.

An easier but not quite as effective alternative would be to fasten a piece of angle iron to the inside of each of your grade beams. If the the span between the beams is less than 8 feet put down a layer of plywood followed by rigid foam. Once the house is in place do your best to fasten the plywood to the floor joists. If the span is greater than 8 feet use 1x4s. We did something similar with our pier and beam cabin. See video below.