SubMetering in Wisconsin

I was reading the old posts here about sub metering. I like the idea of a billing company handling everything, the manager or owner reads the meter and forwards the info and they take it from there. One post I read said the billing company will even add a small amount like $4 as a base charge. One company I seen after googling even said they collect on any bills they send out, does that mean if a tenant doesnt pay the bill, I dont worry about it, they will take them to court for non-payment?

Couple questions I have: 1) I am also unsure of submetering is allowed in WI, does anybody know for sure if it is or not? 2) Can sub metering be done in apartments the same as mobile home parks? Alot of appartments here have shared utilities and the landlord ends up paying utilities for everybody. 3) Can natural gas be sub metered as easily as water can?

Thanks for any info you can provide, I a fairly new lurker trying to find out if owning a mobile home park is for me.