So I got time to check in game today. They are min handling of 7, and the stat def for minhandling does have a specific offset for wildmen. Further though, they have a specific offset to wildness in InteractionWorker_RecruitAttempt of 75%. Which seems to be why the base human has 0 (not that it matters, its hidden on non-wildmen humans anyway), but wildmen have 75%.
Question is: given that wildmen are, afaik, the only time that human wildness matters at all what should be set as the property's value, what should be displayed. I'm happy to specifically display 0%/75% or 0%/75% or something similar, and then the wildness property can be set at 75% so it appears in any automated tables. Be interested in others opinions though.