I would like to install some cellular shades. I'd like to inside mount them, but my window recesses are very small - as little as 1/2". For a shade that requires a recess of at least one inch, one thought I had was to replace the existing decorative trim boards with a simple 3/4" pine trim that is flush to the window frame. This would give me 1.25" of recessed depth, assuming I don't mind attaching the shade partially to the window frame and partially to the trim.
What problems do you foresee with that approach? I would obviously stick with lightweight shades and make sure the trim boards are attached well to the wall.