It may not be delam. A lot of times the front and rear are not bonded panels. On the front the filon panel is just folded over the front and fastened on the perimeter. The rear is the same way and could have a large window or in the case of a rear kitchen it could have the vents and covers used as part of the sandwich process. Our Heartland North Trail was that way. It had what looked like delam but was in fact just puckers in the filon form expansion.
We have a Camping World dealership next to the freeway and when I drive by and the sun is at the right angle you can see all the wavy puckers on the back of the Keystone Laredo TT's they sell.
If you like the trailer and the price is good it's worth checking out. It could just be a cosmetic thing.