I am building an addition with vinyl windows and want to ensure there is sufficient depth on the interior to inside-mount automated roller shades (about 4" of a drywall return with no wood trim). The walls are currently planned as 2x4 and there is a stucco exterior with no sheathing. Here's an example that is roughly the depth I'm looking for.
From what I've gathered, with a 2x4 wall I'll end up with about a 1.5" drywall return as the windows I'm looking at have a 3.5" jamb and a 1" nail fin, (essentially giving me the 1" fin plus 0.5" interior drywall). Window nail fin diagram is here: https://windorsystems.b-cdn.net/wp-content/uploads/1550-Section-View-XO-1-inch-Nail-fin.pdf. Are there typical ways to extend this other than just having a thicker wall?
I could go with 2x6 framed walls, which would increase the depth by 2" Does adding exterior window trim or something around the rough opening (pushing the nail fin further out) make sense? Or does this end up looking strange? What other options do I have?