I can't speak for that model or arrangement, but we have our 4000 located at the rear (pretty much under the floor of our bedroom), and it's going to be noisy, but it's not really all that bad.
I think the A/C makes almost as much noise.....and you really do get used to just about anything, as long as it's a constant...such as a loud rain (without the thunder), so I'd guess that you'd get used to this too.
I work on a Tugboat, so I'm used to having generators or engines running while I sleep:B
I'm not sure how much more noise the 5500 makes, though I'm also guessing that the newer RVs have better insulation and sound deadening.
Hopefully, someone with that set up can comment.