I don't know, but you might get more exposure for your question if you ask it on the Mercedes chassis forum:
https://www.forestriverforums.com/forums/f242/
The Solera brand has been discontinued, but Forest River makes several other Mercedes based units under different brand names. The units are largely similar to the Solera and likely use the same construction techniques.
In fact, it would not surprise me if window installation is similar across a wide variety of Forest River (and non-Forest River) RVs, so you might also search in other forums.
Good luck!
Dave