That is interesting! Is zooming a problem? DrZombi mentioned it in his readme, that it might disrupt the proportions and overlaying. It might be really nice to lock away mouse zoom somehow, so as to avoid accidental zooming (if layered backgrounds and positioning becomes more mainstream, which I hope it will).
An idea I have is using a single, detailed high res image as background for an entire scenario, much like you did with the bathroom. Let's say a bedroom with a side view of the bed in the center. So you can zoom in on the bed head and do a kneeling blowjob in front of bed there. Then you could zoom in on the foot of the bed for another background and do him sitting oral there. Then go into the bed for various fucking positions and getting all fancy with layering the covers etc. You could even simulate tying her to the bed post or whatever. Just seems like A LOT of work for making custom positions for every little thing to get it just right.