Hi there.
By the time you're in position of building wonders, the issue is more overpopulation than low manpower.
Besides that, once the mohole is out, geologists become completely useless.
I really would like to have the possibility to man the wonders, even as a game rule that increases the difficulty ratio.
However as it seems the first one to have this request, you fellow modders are free to tell me if it's too much work for the trouble.
Thanks!