If you do a search on RV Trader, you’ll find they still list the Chateau 28A through 2019 model year. I’ve rented the same Cruise America unit as yours and one difference I see is that the bathroom is reversed. On your unit and one I rented, they place toilet on driver side, with shower on passenger side (which I like better). On other documentation, I often see the toilet on passenger side and shower on driver side, yet listed as a 28A. We’ve looked into your floorplan because we like it a lot, but at 30 ft it’s much larger than we want.
I’d ask both Cruise America and Thor to see if they will share a copy of the drawings you need. You may get lucky.