That’s strange, he was very helpful when i requested the exact same thing, a couple of moonlight specials with 6 modes specified by me. Has he stated he’s not interested or could it just be miscommunication going on?
I think you have misunderstood the specs of the driver, there are already 8x7135s on the board. From the page you link to:
“Low modes (up to 13%) are driven by a single AMC7135 IC (380mA), which allows very low moonlight/firefly modes and makes those modes also quite efficient (the LED is more efficient at lower currents). Medium and high modes up to 3.0A are driven by additional 7*AMC7135.”
You also mention a slider switch, and have mentioned dimmer switches before. These are useful if your controlling factor is the amount of light being emitted as you can control it precisely with the slider but you won’t know how much power is being used and therefore have no accurate way of knowing how much runtime you have which seems to be your controlling factor here. Unless i’m missing something the only way to specifically control runtime is through preset modes where you control how much power is being used at any given time. And don’t forget the modes would control how much current is being delivered to the LED which is different to the amount of current being drawn from the battery due to losses in the system, you would need to factor this in for accurate run times.
As mentioned above these threads are a starting point for programming your own modes:
The first thread explains the process and what programmer/cables etc you need, the second is an example of someone doing it themselves.