@Simmeltron - I am not sure whether I understood your comment quoted above. If you install a smart dimmer you can still control it from the master and/or from the remote… at least this is the case with Leviton Vizia RF+ zwave dimmers. Since you have an existing 3 way system, the extra wire can be used as the traveler to connect the master to slave. My Leviton switches came with easy instructions on how to wire it all up.
On another note, I’ll tell you my setup in case it may be of interest to you. My front door light and my driveway lights both turn on together via SmartLighting app so I don’t have to walk to both switches (either one will turn the other on as the assumption is I would always want both sets turned on at the same time). The SmartLighting app turns them on/off based on sunrise/sunset however for the driveway I used a switch and for the front door (porch) lights I used a dimmer. The dimmer turns on at 20% as a default which is still plenty of light given I installed two 120W equivalent LED PAR38 bulbs… if it is linear then it may be around 50W equivalent of light. I then added a motion sensor pointing down at my porch so that any movement causes the lights to go on to 100% for a short while (or as long as there is motion) and then back down to 20%. This only happens when the lights are already on. Aside from the cool effect of the entrance glowing brighter when someone approaches my front door, it saves energy, and it may scare away potential intruders as it is a sign their presence was already detected. The motion sensor is attached to the same junction box where I have a dome camera so if they look up to see why the light turned brighter… say cheeeeeese This actually happened in several cases. The difference between regular motion lights and my setup is that my lights are always on but they just glow brighter when there is motion. I am not worried about false motion detection as the 120W equivalent LED bulbs actually only use about 23W more or less.