Confirm with the dealer that they will do a full test of all components, don't buy "as is, where is". Dealer should ensure all electrical works, battery good or new, propane recertified and drop tested, water system pressure tested. You should arrange a PDI where the dealer demonstrates to you that all of these things are operational.
Check tire wear and age. You should still have 2 years left on tires by serviceable time, but are they wearing evenly? X17Z has very low CCC, so if former owner abused it, it will probably show on the tires.
Take a very close look at the shell looking for any sign of delamination - these are waves in the smooth skin. That is usually a sign of water infiltration. Take a look at the roof if you can as well; any signs of tears or repairs? Has the Dicor been kept up (fresh looking or old and peeling sealant).
Take a close look at the bunk ends for any holes or tears. Easy to do in bright sunlight, or sine a bright flashlight and look for pins of light on the inside.
Note that buying used is great, because you can generally turn around and sell for about what you paid if it turns out to not be the unit for you. Buying the wrong unit new can be a financial disaster.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP