“The pilot attempted to troubleshoot the engine” At 400 ft the pilot should not have wasted his time on a checklist, but prepared for an engine off landing.
At 400 ft he was just about at the right height for a safe landing in a glider, but NOT in a dead-stick stink machine!
These post flight fires in front of the fire wall could be extinguished with a light weight fire suppression system. So many times I see a crash where the crash looked survivable… but the plane burst into flames. Hand held Fire extinguishers are useless to an injured pilot. They are good for controlling small cabin fires.
But, a fire fueled by the aircrafts fuel system need something a bit more effective and in front of the fire wall. I’ve seen fire suppression balls online that look like they work well.
The elide fire extinguishing ball weighs 1.5 lbs, and only goes off when exposed to fire, not heat. It is currently marketed to boaters, and race teams. Experimental aircraft pilots may want to use these. The rest of us may want to push for this type of system to be used on certified planes.