Reddit mentions of Aeotec Nano Dimmer, Z-Wave Plus In​-Wall Dimmer Switch for LED, Incandescent, Halogen, Fluorescent Lights, ZW111 1.2A Neutral Optional, Read Power Consumption

You should be able to use these https://www.amazon.com/dp/B06XC4CH98/ref=cm_sw_r_cp_api_464Qzb0DXP5YD

Aeotech makes the micro dimmer and newer nano dimmer that do the same thing, but using the zwave protocol.

Aeotec just released a dimmer that doesn't require a neutral.
https://www.amazon.com/dp/B06XC4CH98/

My bad. I didn't realize there wasn't a switch anywhere. I was assuming it was just in an inconvenient location. Not all hope is lost however!

You could hard wire an in-wall controller above your fan similar to this. You may still be able to pair it with the accessory switch, but you could at a minimum pair it with a scene controller.

I had a similar problem and I wasn't going to share neutrals between separate circuits (probably a code violation unless you link the breaker switches to go on/off simultaneous). If you don't mind a dimmer, I used this :

https://www.amazon.com/Aeotec-Incandescent-Fluorescent-Optional-Consumption/dp/B06XC4CH98/

I had another situation where I had a 3-way switch downstairs and one upstairs with a light in the middle. Because of this wiring arrangement, I didn't have enough wires to use a companion switch (HomeSeer), so I simply powered a standalone switch using the opposite circuit and will have it simply control the upstairs switch via the controller or a scene.

What do you use to control the fan? I have a homeseer dimmer to control the light right now. Not sure how to control the fan. Would the Aeotec nano dimmer (https://www.amazon.com/Aeotec-Dimmer-lighting-controller-dimming/dp/B06XC4CH98) work? Website says can control fan up to 100w.

Someone else this recommended this to me for fan control. I haven't jumped on things yet for fan control though. Aeotec Nano Dimmer lighting controller, Z-Wave Plus, In-wall, Light dimming https://www.amazon.com/dp/B06XC4CH98/ref=cm_sw_r_cp_apa_i_P2iaBb6H8Q40X

For a stand up fan I ended up just going with an IR one. I am a Homeassistant user so it was pretty easy to add it in with my Broadlink mini IR blaster I had already for turning the TV on and off. A quick Google shows they have a smartthings handler for it.

i think you could theoretically replace all the light switches with these, and then you could just throw a tablet where the switches are now running a front-end for whatever platform you use to manage your devices.

I'm not 100% on this, but I think you could install a relay such as this in the lighting box where your power is coming in.

That's common in older houses. The power line from the breaker box is ran to the fixture, and then a two-conductor line goes from the fixture to the switch. That puts the switch between the hot and the fixture, but has no neutral.

You have a few choices here.

One is to use a switch that doesn't need a neutral wire.
The Lutron Caseta line has a couple that don't need neutral.
On the Z-Wave side, a company called Inovelli has a dimmer switch that doesn't need neutral coming out in May but pre-orders are available. Their head guy is a Redditor- /u/inovelliusa
There's also a GE/Jasco Z-Wave dimmer that claims no neutral is required- the Jasco 14299. Spec sheet says it won't work with CFL or LED, incandescent only.

Two is to run a neutral wire to the switch box. Generally this is done from wherever the nearest outlet is.

Three is don't use the switch as a switch. Put something like a nano dimmer in the box above the fixture, and bypass the switch entirely. Put something like this over the wall switch, or alternatively you could use the line going to the switch just to feed power to a z-wave powered keypad like the Cooper scene controller.

Aeotec Nano Dimmer. Works with or without a neutral (2 or 3 wire), designed for LEDs, and Aeotec gear is SmartThings integrated via Z-Wave so no need for a Lutron hub: https://www.amazon.com/dp/B06XC4CH98/ref=sr_1_1?ie=UTF8&qid=1488199180&sr=8-1&keywords=%22nano+dimmer%22