That is a common complaint with the sleeping layout.  We have had our 177 for eleven years and fortunately we are still young enough to where this is not an issue.  Going from a pop-up it was a jump to luxury.  No more canvas and the eventual smell that goes along with it as it ages, as we usually boondock and camp in the shoulder seasons where weather is inclement or cold it is so nice to have a furnace, hot and cold running water, a toilet, a shower, fridge, cook stove and an area to where you feel cozy and not be the recipient of drafts and the like.   We have been blessed.

Because we are usually in a location where there is no electric we special ordered our R-Pod without A/C, microwave/convection oven, or entertainment system.  Eleven years later - no regrets.

To replace the ceiling panel,  you will need both the panel [or vinyl covering if you're going to make up your own panel] and enough seam tape to cover the seams.  The panels are generally stapled to the ceiling framing so it's not hard to remove and replace it with a new piece.  It might be a good idea to heat up the seam tape that goes around the panel you need to remove with a hair dryer, so it can be pulled off without damaging the remaining panels.

Good luck with your project.