You might want to talk to the vintage group. They may even have some of the blinds from yesteryear they are taking out to install day/night shades in!
Ah, now I remember those were rollup wood blinds. Sorry, my bad.
I am not sure that 2" will work considering the valance clearances but on some coaches it might. I have seen some coaches where the day/night shades are so cramped for space they are very difficult to operate.
Most day night shades are screwed up into the top of the valance. The wood shades could probably be mounted the same way.