Having seen the state of the emergency vehicles/ hospital transfer vehicles I’m sure it’s not difficult to make your own with few stickers and flashing lights !!
Most of the ones I have seen here in samui are pick ups with cab roof on the back, dodgy boy racer alloy wheels , more stickers visible than paint , lowered suspension , low profile tyres and enough lights for a Xmas display !! The sight of them makes me think if the accident I was didn’t kill me or disable me then being transported to the nearest hospital in one of these would !!