I have used Eva-Dry units with my RV since I got it back in 2011.
The good: They do work in small spaces without much airflow.
The bad:
The effect from them was at best marginal. They were useful in a closet or in a cabinet, but the inside in general? Almost little effect.
They require being plugged in for a number of hours to regenerate. So, they went on a baking pan and an aluminum table outside.
You will be in a world of hurt if you drop them. All those little silica beads will go -everywhere-, and it will take a while before you manage to vacuum them up.
My recommendation: Damp Rid products do work. However, if they spill, they are caustic, so they need to do into a secondary container like a five gallon bucket or a strong plastic tub. This way, any mess is well contained.
The best of all worlds is a real dehumidifer. Eva-Dry models just don't cut it. You need a compressor based model. Ideally, you should be able to place it the shower or bathtub and have it drain into the black water tank, so you don't have to empty it that often.