I'd check to see if the problems are still happening. The floor of the trailers made by Riverside are made out of OSB and the enclosing material is more along the lines of the material that is put down on the ground to stop weeds from growing in your rock beds. There have been several problems of the floors getting wet and rotting out. Also, the wheel wells have had problems with leaking when towing in rain/wet conditions.
Your mileage may vary...but the wife and I had planned on getting a Riverside Retro trailer until we actually saw one inside. The Birchwood paneling that you see inside is actually luan ply covered with a birchwood looking vinyl. The wall joints where the panels meet are just covered with an approx 2" wide strip of the same vinyl that was bubbling and peeling off the wall while sitting in the dealer's lot. After pushing it back down, within 60 seconds, it was popping back up again. The sinks are very thin plastic...very thin as in you can almost use your fingernail to leave a mark in the sink. Same for the bathroom surround in the shower.
As I said, your mileage may vary...but we looked at the 180R and the 189R...while not the same trailer you are looking at, it IS made by the same company. The fruit doesn't fall far from the tree so to speak.