Unlike most of my projects, I decided to design the circuit and PCBs first before any testing or programming. 

I found a circuit example to produce 0-10v analog voltage signals from the pwm using an opamp:

This was originally designed to control a spindle and was designed for use with an arduino. The x2 gain means a 5v pwm would output 10v. The ESP is only 3.3v so I changed R3 to be 32K. This gives a slightly higher than 10v at full on but the lights are tolerant of up to 12v and 32K is a common value. 

I bought some opamps and while waiting for them to arrive so I could test my idea, I started on designing the circuit boards. 

Here is a timelapse of the board design:

My initial design was to have the ESP + opamps all on one board called the "control board" and have the 0-10v signal for that go out to the lights over RJ45. The modules at the lights would have two RJ45 ports on it to allow daisy chaining between multiple lights, as well as a 4 position switch to select which of the 4 dimming channels that particular light would be controlled by.