All the components I got for this mod!
To the left are Seoul SunLike 3030 LEDs in the 3V, 5700K variant, which are the objective of this mod. The large reel in the middle are 3V 2835 emitters in 5000K–the soldering footprint is essentially the same, and they are cheap enough for first experimentation.
The paper reel on the right are R050 resistors, for the purpose of swapping into a Convoy 5A linear driver. The original driver has a R020 resistor, and swapping these in should reduce the current from 5A to 2A, to not overdrive these emitters too much. The resistor footprint is 3216 in metric units, 1206 in imperial.
Down there is a PCB I intended to flow the SunLike emitters onto. It comes with 6 2835 emitters stock, and I figured that I could scratch off the solder mask and flow more than 6 emitters onto the same PCB. Thanks to u/crbnfbr for assuring me that this is feasible! The 24mm is too big to fit into a S2+, and I figured that sanding the edges might reduce it to 20 or so mm without losing too much of the outer trace.
The combined cost of the 5700K SunLike (20x), the pack of resistors (50x), and PCBs (10x), came out to $7.6 without tax, around $8.3 with tax and shipped. I got them with another order during an aliexpress sale, so shipping was free. Therefore, with an existing S2+ triple with 5A linear driver, and access to basic tools, under $10 is required to perform this mod.