Is non turbo diesel better than non turbo petrol? Not sure but history would suggest that as both the Willys and Land Rover series 1 were petrol and survived the Second World War that petrol is king in the most challenging of circumstances. Good call.Turbo engines and diesels especially will break catastrophically with water added and it does not take much, about half a cup full for a BMW X5. (My Grenadier was anticipated to have 2 bent con-rods, but the turbos were consider scrap).
A low revving petrol engine with a lower compression ratio is more likely to survive, (and much easier to fix).