We're only recently part of the skoolie community. For the past 6 years, we were exclusively involved in ambulance and coach bus conversions. Right now, we're working on two different ambulances...a medium duty and a type 3. There's a ton of helpful general information here, which might help you, but for ambulance conversions I think you're better off looking at the Expedition Portal Forum. For a basic conversion, leaving much of the original interior cabinets in place, you could also check out the YouTube channel of The Campulance Man. I can't help you with your Wisconsin question, but generally any RV conversion requirements will be the same whether it's a school bus, coach bus, box truck, or ambulance...so some WI member may be able to help with that info.
Ambulances are great conversion rigs - heavy, but oh so strong.