The AMR operation I work for just permanently converted a Type III that had too many miles on it to meet the 911 contract's requirements for front line service. It's a fully stocked ambulance minus bags and a monitor. When a scheduled transfer comes in, the transfer ambulance will return to base and grab it. When it's a 911 call the supervisor or someone else at base will bring it up. It's got a stryker bariatric cot, winch, and ramps. It's utilized fairly frequently so long as time isn't too much of an issue. Another option is utilizing the wheelchair vans. If the patient is too large and is able to remain in a bariatric wheelchair despite their illness, a van will be dispatched and the patient and one medic will be transported in the van. Not ideal, but far more comfortable for the patient.
My full time place does not have anything. In theory we could call AMR and have it come up mutual aid, but realistically we're just going to work around it, for better or worse. Our neighbors have a Ferno Cot that they can place the LBS thing on to make a pseudo-bari cot but it only fits in their fourth line ambulance which isn't always stocked or in service.
I have worked a bariatric ambulance that was a Type II. Those were some bad days.