I don't know about Eclipse - but I tried setting up Unity with the official Unity IDE a few years ago. And that worked quite nicely - the only problem I found was that the graphics card on my laptop doesn't have enough grunt to be able to run many of the Unity engine's features.
So I could learn to use Unity. And I could build applications using it, but I couldn't run any of them properly on my PC. So I gave up trying to learn Unity. I gave up trying to learn Vulkan with C++ because of exactly the same problem too! I really need to get a better laptop, or a half-decent workstation!
BTW - The Unity IDE is basically Monodevelop! So Monodevelop might be an option?!
Your best bet might be to ask in Unity's community forums.