We took the trailer to Desert AutoPlex, the Coachmen dealer in Mesa, AZ. Unlike the first dealer we tried for warranty work (Galpin Ford RV in Dewey, AZ), Desert AP was very prompt addressing the issue.
Jill, the warranty dept customer service person, has been very good about keeping in contact via email and phone.
We took the unit in on Wed, the 31 of August, and she promised that a tech was waiting to look at it. When she first walked in the trailer, on the squeaky floor, she said, "oh my, something is not right!" and that she had never seen similar movement and creaking.
Thursday or Friday they inspected the floor, cutting away the fabric beneath the trailer, with one tech walking inside, and another underneath watching. They determined that major repairs would be necessary, and they would contact Forest River for authorization.
Monday the 5th I got this email:
"Ok we got auth to start the work we wont have to take anything out from the inside what Factory recommends is that we add 2x2 to soft areas to support add liquid nail and glue to support and let dry for awhile I will keep you posted the tech That will be working on this is good
we will get this right for you"
Poor email skills not withstanding, (I think she uses voice recognition on her phone to write emails!) it looks like they are making an attempt to fix the problem.
She didn't say what the 2x2s are - alum, wood, steel or what - but I presume wood, since they will use Liquid Nails. Not sure how much rigidity will come from 8' lengths of 2x2s, but we'll see.
Daily high temps in Mesa have been over 100°, so it should not take too long for Liquid Nails to set up...so I anticipate hearing something from Jill this week.
Again, I'll keep you posted...