I had a similar experience flying a deceased individual from Kiunga to Daru in a C-180 back in the early 60s. The body had been badly burned and rigor mortis had set in. The only way to transport him was in the back seat of the aircraft.
Not having anything to wrap the body in the local Kiap had lined the seat with some palm fonds and thrown some over him as well.
The worst part of the flight was the overwhelming smell of burnt flesh.
Not a flight that I would like to repeat.