And how would one know if his ambulance was an emergency responders or a morgue transporter
Like anything it’s just a matter of doing your research 😉
A lot of non NHS ambulances will have had relatively easy lives; think of how often you see medics ambulances at events, doing not a lot; that said, a lot of the ones with 350,000 miles plus are emergency ones, so the horrors of cold starting can’t be too damaging.
I’m curious to see if having a coolant heater effectively gives you free-ish energy by reducing fuel consumption; of course, it burns a bit of diesel itself, but is that negated by the engine already being warm at start up?
Back to OP, it’s worth considering the width to allow a cross ways bed, giving you more flexibility with layout, also bear in mind the lower floor of front wheel drive vans should give you better fuel economy and handling.