I have decent luck with single-leg in ERG on my Kickr17. These are often done at lower resistance levels. I think my last ones were around 50-60% of FTP. I suspect it would be more difficult at levels 70% or above, but don’t remember if I have ever done them like that.
This is a recent workout. Look at the steps leading into the first work interval.
https://www.trainerroad.com/career/chader09/rides/46313967-tunnabora