There should be the option to save map data to Cartography 'Banks' in rental safe deposit box sense in station services, so there are 'checkpoints' of saved data?
Another moral of this story is sell map data every time you park where possible. save game, resume. Rinse, repeat.
This doesn't help - explorers don't have stations or any way to sell the data until they get home, and if you're already in human space, then map data is in the same boat as bounty data, vouchers, etc; they're not as large an issue because people don't carry such large quantities, because they're able to sell at their convenience. etc.
Redesigning how people should play the game rather than fixing a bug is a bad solution to a bug. It's less work to fix the bug.