There are fast-drying fountain pen inks designed especially for left-handed overwriters. Have a look at Noodler's Bernanke series, for example: https://noodlersink.com/product-tag/fast-drying/

Funny story, the inks are named that as a commentary on Quantitative Easing. So much cash had to be printed so quickly, you see, that Bernanke really needed the ink to dry really fast...

Hmm, not sure, it works for me. I mostly use Pelikan dark green or black ink. Seem to work well enough for me.