A way of eliminating the need of resistors is using a linear voltage regulator on each string, on CC mode (with a sensing circuit with a small resistance).

Linear regulators are problematic when they must reduce many volts. But when they only need to reduce voltage on some tenths of a volt, they work pretty well. And they are cheap. And that way you are controlling directly current of the array. Way better than the resistors way (although still worse than a switching CC driver, way easier to do)