Betsey, we bought a 2004 31DA on a Workhorse W-22 chassis with the 8.1 engine.
We do quite a bit of boondocking, and found it necessary to increase fresh water capacity on our coach. Easily done, just added another tank along side original under bed and connected the two together. I also found the water pump located in the utility bay to be really noisy. It is mounted to the back of the bay wall which is sheet metal, and really amplified (can you say drum) the noise when pump was running. I moved it inside under bed next to water tank.
You didn't mention what chassis you ar looking at. Be aware that there have been some brake issues with Workhorse chassis by some owners. Also an on going problem with instrument cluster that requires frequent replacement. I have had 3 in five years. All in all, I like the size and layout of the coach. Completely useable without having to deploy slides, which comes in handy at times.(Wal-mart)

Hope this gives you some insight on your planned purchase. If I can answer any specific questions, feel free to ask.
Dieselclacker