I wouldn’t do that.
While poison ivy is normally naturally occurring, cultivating poison ivy may be seen as artificially creating a hidden danger on the land. That might make you liable for someone else’s injuries, because you’re as likely to harm an innocent person as a trespasser.
Meter reader, neighbor’s kid with a wayward ball or an errant puppy, UPS delivery guy in shorts — urushiol don’t care. You could fence it all off in a poison garden, but that would defeat the purpose.
Perhaps you could post signs warning of poison ivy, but just not planting any more than you already have, the way fake minefields are sometimes posted in wartime.
Too, failing to remove existing poison ivy might be a violation of local ordinances. Poison ivy is a defined as a noxious weed requiring removal in Lexington-Fayette County, for instance. See https://library.municode.com/ky/lexington-fayette_county/codes/code_of_ordinances?nodeId=COOR_CH12HO_ARTIINGE_S12-2NU.
This is a blog post, not specific legal advice. No attorney-client relationship is intended or created.