I could go in for poly-fidelity myself, but it would have to be outside of marriage, because there is NO WAY I want more than one husband. Many lovers would be nice - one for each day of the week, I could just call them by the day allocated to them, to keep them easy to remember.
As long as I never have to do their laundry, pick up their socks, discuss their career progression or cook their food, look after them when sick, or bear their children I think it would work out really well for me.