Sorry, I meant the separate Waves dither plugin that’s called simply “IDR”. It’s a whole different plugin, a standalone dither plugin, in the Waves folder. It used to come free in all Waves installs. Is it not in your Waves pulldowns? I was just suggesting using that rather than the whole L2 in the dither slot, but if the L2 is your last plugin, might as well use it in the dither slot and dither with the built in L2 IDR, or the before and after you originally suggested (the first, dither bypassed and the second, limiter bypassed).
If the L2 was not the last plugin in the chain, and I wanted to turn off the included IDR, I was never sure if the IDR in the L2 was ever completely turned off. In Waves v7 it always indicated 24 bit output, so was not sure it was not dithering to 24. Maybe it can be completely turned off in v9.