Going from 72V to 5V with multiple switching regulators
What about the LM5017: -



It can do load currents up to 600 mA. There's also the LT8303: -



This has an isolated output.


  Can I put two of these in series?


You can stack switchers in series. For instance, you could use the LM5017 to drop to below 60 V (say 50 V) then use the LMZ36002 to finally convert to 5 V allowing you to get the full 2 A from it.