I have quite a lot of that generally 'undesirable' plant in the less tidy pieces of my garden. I use them as mulch material, and to make liquid fertilizer, for which they are awesome.
I get stung almost daily, on my hands, arms and legs, and it seems to me that one can develop some kind of immunity for them. This is highly subjective, I don't have proof, and it might not work for everyone, but that's the way I experience it. The more I get stung, the weaker the effects seem to be.
I had no idea that poison ivy is Rhus toxicodendron. It doesn't grow here, or only in a few places, where it was planted (people and their short sighted love for exotic species... I don't like it, but anyway). Personally, I think a good part of what's called homeopathy (specifically the "dynamisation" or "potentisation" by "succussion") is a load of BS, but not everyting, like e.g. Rhus Tox or ointments made from Calendula officinalis, even though in some cases evidence for their effectiveness is not exactly strong. That being said, I consider those medicine based on natural ingredients, not homeopathy per se.