As Cookie mentions, running a wire in the ceiling is difficult. I believe your coach has a block-foam laminated ceiling - so, really hard to run a wire in it. And then there's the issue of getting the wire into the ceiling from the soundbar that's in a slide.
Consider this instead...
Route a speaker wire from the sound bar, down to the base of the entertainment cabinet and out a small hole in the slide room floor next to where the coax cables come through. Then route the speaker wires along with the coax, through the flex guard and into the same hole in the frame.
Remove the screws and washers along the edge of the frame that pin the coroplast up so you can reach into the frame and locate, then pull through, your new speaker wire and route the wire in the underbelly, forward until you reach the area of the UDC. At that point, fish it up into the utility area through the area where the main deck meets the drop frame (storage deck). From there, route up to the bedroom in an area that best suits your needs.
There are ways to get the wire up to the ceiling at that point but still, fishing it within the ceiling to where you want/need is going to be tough. You could route it inside the air conditioner duct. I have successfully done this. Hope this gives you some ideas.
Alternate underbelly wire fishing process and how I do it...
- Gather a number of fiberglass wire push rods (I have cheap ones from Harbor Freight)
- Remove the rear-most wall that separates your storage bay from the utility area behind that wall
- The step above, exposes the gap between the main floor deck and the storage floor deck. Keeping it as high as possible, in the center of that gap (left-to-right), push your first rod back towards the rear of the coach
- Continue to add more rods to the end of the previous, keeping the long rod as high as you can and keep pushing them rearward
- Keep note of how many sections you've used and their total length. When you can push no further, armed with the knowledge of how many feet back the end of the first rod is, over on the off-door-side of the coach, remove screws/washer for about 4 feet of underbelly
- Push the coroplast, flex foil and fiberglass insulation down so you can get a flashlight, your hand/arm and maybe your head into the underbelly to look for the end of the fiberglass rod. Find it and pull it out the opening you put your hands into
- Carefully and securely wrap, then tape your speaker wire to the rod
- Go back to the storage bay and pull the other end of the rod out, removing sections as you go until you've pulled your speaker wire out
Half the battle is over. Celebrate, then get back to it!