We picked ours up in May, on the walk through there is so much info to absorb so take a notebook with you to jot notes. I really made sure all of the options we ordered, were installed. We had the dealer install a second safety latch on the main door for when it is open so the wind does not blow it shut. We did a metal one, plastic ones will eventually break. The friction hinge is ok for a light wind but if you get a gust, the door will slam.
In the bunk room - the back wall, make sure to clamp down on the curtain rod ends, it will fall off and it will get crushed by the slide out. Ours did and I made sure the new one will not come off.
I would also suggest swapping out the (2) door straps on the bunk room and bunk room bathroom, kids open them and wear out the buttons, i am going to install the one like is on our closet which is a metal bar. We had an incident where the bunk door was not strapped or the strap came undone in transport and when i put the slides out, the door handle got ripped off and the hinge doors were bent. Was a 2 hour project for me to swap in a handle from Home Depot and pull the hinges off and flatten them back out.
Switch for the electric water heater is on the outside panel on the water heater, we used gas for about a month and finally figured out we needed to turn it on manually each time to use the electric and not waste our gas. Remember to turn it off when not hooked up to water so you do not have it running on an empty water tank.
Check all counter tops to make sure they were caulked from counter top to to wall edge, they missed a few when they built ours. Also check the door bar in the shower to make sure that is caulked.
So far - we are very happy with our Sandpiper. Just like a new house, there are minor things that go wrong that are a quick fix or just add to a punch-list for the dealer to fix after a few run downs.