4000m is a long way down. In terms of design modifications to achieve retention and transmission of information, it's all fixable ... for a price. Wreckage location: simple buoy to be released following g measurement exceeding preset level (crash). Buoy contains GPS receiver/data logger and beacon, retrieve buoy and download data logger to locate release point. ELF receiver to trigger further buoy release (assuming USN ELF system is still in operation?), ELF signal to be sector specific (but I doubt if ELF can reach to 4000m). Buoys may contain flight data loggers, data to be stored on (several) SD cards or similar.
All adds weight/cost.