Are you referring to the "frame-less, pop out at the bottom windows? They are restrictive to air flow but you'll get a lot less chance of leaking with them and you can use them even if it's raining. But to answer your question, if you can find a window of any type that will fit the cutout, it can be installed. Check with Thor for the exact dimension of your raw cutout first.
2018 THOR Chateau 35SF
Two Labs, Bugsie & Blondie