One thing I noticed about observing in the desert ecosystem is that there are seasons where the winds will blow with much strength. Acquiring information about wind patterns and gusts that are typical of certain seasons is the key. In the southwest where I do most of my observing (primarily the Death Valley, Mojave, and Joshua Tree areas), winds are strongest during the spring months, and they almost always blow from the south, southwest. During these periods, I bring my refractors. After spring, the desert dies down and only the heat remains for much of the remaining summer.
That said, I wouldn't be too worried about the dust as much how a larger scope "catches" the wind due to its size. Is your observatory going to be the slide-off roof version? You'll catch a lot more gusts if your walls are not high. I loved going to the desert during spring to welcome Omega Centauri with my former 10" non-dobsonian reflector. The winds just shook the OTA to the point that medium to high magnification would cause the observer an immediate headache and nausea due to the shakes and you'll stop observing before any dust/sand issues plague your scope. A smaller profile scope is rather invisible to strong wind gusts and this is where my 6" fast refractor comes into the picture.
Another attribute to consider is observing time. Again, I can only base my experience with the Southwest USA: if I head out during spring, I actually sleep early and wake up around 2AM to observe until dawn. Even in spring, most winds die down by the wee hours of the morning and an eerie silence permeates the entire viewing experience. Indeed, observing during the wee hours of the morning during most nights of the year in the southwest is what I consider to be the most ideal time since the temperature change from twilight to night is no longer a factor that could generate wind gusts.
Edited by nightowl, 14 October 2021 - 11:00 PM.