RonJ,
The rear twin bed model you are curious about was last listed in Phoenix's 2011 brochure, called model 2950.
- over-all length 29'-8" (model 2552 is 27-10")
- wheel base 208" (model 2552 is 206")
It seems to have an extremely large rear overhang compared to model 2552, placing a lot of weight on the rear axle. It's saving grace is that like 2552, it does not have a rear slide out to weight it down further.
- fresh water 46 gallons
- black waste water 23 gallons
- gray waste water 35 gallons

If you got the dinette without the front slide out, it would be much more comfortable with a bigger table and more leg room. The over-all weight would be reduced by roughly 500 pounds.
It seems to me that model 2552 has the optimal length-to-wheel base ratio for load distribution and handling.
Send me a PM with your email address and I will email the 2011 brochure, and maybe an older one if it has 2950 interior pictures.
One of the other Rons