Yes, this is tricky. It may depend on what you have in the remaining voices/hands/parts, but one possible solution is to use stem direction to your advantage:
By using stem-down notes for the held Cs and stem-up notes for the moving line, it minimizes the confusion on the large beat 3 (where earlier the E looked as if it came after the dotted-quarter Cs).
There are a few weaknesses here:
- The dots on beat 3, which can certainly be moved closer to the Cs as desired.
- The hidden dotted-quarter rest on beat 1 looks a bit swallowed up here. But I'm assuming that a moving line in another voice will clarify where this first E is placed. If not, I'd recommend making that rest visible.
- Lastly, these stem directions may not make any sense with your composition; if the held Cs are really viewed as an "upper voice" in this staff, then this may not be an ideal solution.
A scorched-earth solution may be to just briefly include a third staff (think of the famous Rachmaninoff C-sharp prelude here), but that should probably be your last resort.
Alternatively, you could write one of the voices with smaller notes.
I'd be curious to hear what recommendations others have. My sense is that this may just be one of those examples that will always look a little wonky, but I'd love to be proven wrong!