Many posts claim that shocks are not needed, but that Airstream puts them on because AS are "high end" products and they would be considered lacking if they weren't included. I can live with that on good paved roads, occasional potholes notwithstanding. However, if you encounter a dirt road with washboards, I can't imagine feeling comfortable without them.
Andy at Inland RV has the right shock (if your's is a horizontal installation). You can look around the forums and you'll see two different alternative shocks. I picked Monroe 555003, intending to put them in horizontally. Some quick tests (pushing and pulling them by hand) in a nearly horizontal position indicated they maintained damping action in this orientation, per others assertions. Ufnortunately, you'll find differing opinionson this and I can find no specs for maximum installed tilt angle for any shock. Nor can I find a shock that says "for horizontal applications." Maybe someone else has a URL for this information.
After I bought the shocks, I wound up taking the belly pan off as part of an axle replacement effort (see "new axis axle" thread). Now that the belly pan is off, I can install an upper shock mounting bolt that will allow nearly vertical shock installation (38 degrees from vertical). If I made the shock bracket longer, there would be no problem making it truly vertical. I'll post drawings on the other thread, as well as final installation info once I get the axle installed over the weekend.