We bought the things called "dry-z-air". It's a waste of money. It's just a plastic holder for Calcium Chloride, used as driveway ice melt. Then, we bought a 55 Lbs pail of it at Sam's Club. A bit overkilled just to use as de-humidifier. You can get it in 3 or 5Lbs bags, use some kind of mesh bag and hang it in your shower over a plastic bucket.
The other way to go: dehumifier for RV
. We were going to get one, but we read many comments from people who found them too noisy.
Last thing: some people use their A/C even while running the heater. This will help dry the air.