Could you not use a delay on the power supply? Only adding One capacitor could do the trick
Adding a capacitor on the TPS_EN pin to ground, after the 2 diodes should do the trick.
Depending on the internal resistance of the TPS_EN pin, you could also want to add an discharge resistor parrallell to the capacitor.
The capacitor would be charged true the diodes, and keep the PSU on for a while if the LATCH_TPS-signal goes down for a while.
Then just modify the software and bootloader code to turn on the LATCH_TPS as quickely as possible after reset.
Kind regards,
Hans