What? How can you have a water heater in an enclosed area? Don't they have to vent outside? Aren't they designed to have the access panel on the outside of the RV?
A look at the brochure states a gas/elec water heater. It has to have access to the burner and elec element from the outside. Are you sure you know how to change the element? Should be a 10 minute job from the outside of your rv.
I'm looking at pictures of Jayco Embarks on the net and I can clearly see the water heater access panel between the slides on one model.
Something in your OP doesn't pass the smell test.