We had a rear kitchen 2009 Sundance. We loved the floor plan. We would still have it, but we could not keep things in the cupboards and the refrigerator. We had to empty the frig into a cooler while we were traveling and tie the cabinet doors shut. Dishes were broken. We even had the frig door come open and broke off and was on the floor when we stopped. This was while we were on freeways and paved roads. You wouldn't believe what happened on gravel roads.
We read the same things on this site that most are saying now how they love or hate their rear kitchen before we bought. But we had to learn for ourselves.
Go back to that salesman....I think you found an honest one. The reason they had none in stock was because the dealer had complaints about them and does not stock them anymore.
I did have a salesman tell me that units with 10 in. I-beams solved that problem, because there was less flex from the axles back.
Buyer beware.