Anyone have CRT shader suggestions for the RP2+?

I'm trying to find a good CRT shader for RetroArch to preserve transparency effects (like the waterfalls in Sonic 2) and dithering. The problem is, a lot of shaders that are lightweight enough (easymode, lottes-fast, etc.) don't seem to do the trick, the ones that work well (sonkun, royale) are too heavy for the hardware, and some that might be solid contenders are made for 1080p+ resolutions and create giant, goofy scanlines at 480p.

The handheld systems are so easy with the lcd-v2-color shaders, but finding a good CRT shader for home console emulation has been tough with this device.

Anyone have a good recommendation?