Hamster Clade

How? Your skin would contain opsins, but it is covered in fur. Chromatophores work for active camo as the integuments contain opsin, as well as significant a significant amount of neurons. 

How would you want them to work, like cephalopod or like that of chameleons, or other of your own design (that legitimately works)? A Cephalopod design is the most effective, but very costly energy wise. A chameleon's by comparison is cheaper, energetically, but is not as effective.

It will take a few turns to develop the necessary goods to use active camo. Whether you decide to lose fur or hook up your fur. None of the above is actually considering textural camo (which is often thought of as part of active camo, but is actually "technically" a separate phenomenon, which is not possible in mammals due internal skeletal support. Cephalopods, even the mantle using cuttlefish, use a hydrostatic skeleton system, allowing them to change their skin's texture and shape. A mammals skin is too thick and elastic, and to make it able to change textually and shape wise, would require a hydrostatic skeleton, which would require a completely water bound existence, and severe reduction of skeletal components.

Okay, but how do you want to develop it? In your hair, or your skin? If in your skin then how do you want it to be visible? Transparent hair, lose your hair, what? Mechanism is everything.

The main issue is that your fur obstructs the view.

Instead, you could simply make the fur transparent.