Our Motor Home is stinking moldy, how do you deodorize the bed?

Mold ? Throw it out and buy a new one.

Commercial cleaning, as they do on couches and chairs, leave in sun and air to freshen.

Mold is a fungus (several, actually). You will have to change the conditions that allowed the mold to grow in the first place before you can get rid of the fungi before you can get rid of the odor. That means drying out the motor home, then killing the mold, THEN deodorizing.

Drying out the motor home can be as simple as investing in desiccants or as complex as installing a dehumidifier into the a/c system.

The mold can be killed with any of several disinfectants. Look for "kills mildew" on the label. Which one you choose should be determined by the fabric in the motor home. Chlorine bleach does a fantastic job but will destroy prints and dyes.

Most stain removers do a good job of removing odors as well as stains. Cyclodextrin is probably the best odor nullifier, but in the U.S. you will have to buy the patented "Febreze" products.