I'm not sure which models have a pantry/cabinet similar to our 2529RG, but in response to some of the modifications that I have seen discussed:
1. adding a grate to prevent items from going down into the duct
2. adding more than the small deflector to direct the heat out, and prevent heat from going up the wall causing the thermostat to prematurely shut down the furnace
3. being able to access/inspect the shower plumbing
I decided to take out the bottom shelf in the pantry to be able to gain access to the area. The shelf is held in place by staples. The shelf will probably not be in useable condition after removal. I plan to replace the shelf with a piece of 1/8" plywood stained to a similar color. The replacement will be held down by screws that allow it to be removed.
Once the shelf is out it will be easy to add insulation to prevent heat from going up the wall, add to the small metal deflector to push air out, add a piece of hardware cloth to the front to block objects from getting into the duct, and occasionally check for leaks under the shower. Our trailer has a small panel under the shower that allows checking the drain (ours leaked on delivery), and I want be able to check for possible leaks from the water lines going to the shower.