It is clean and sustainable, but if you want to do some calculation based on that new field, you cannot do it without programming (make a new module).

Also when you reinstall the database (for whatever reason), you have to do all the things again in the new database. So document your steps, with the exact same wording and capitalization.

Given the above, I prefer to make a module and install that. This guarantees you will always get the field (with the exact name), and you can easily do more with that field (use it in a calculation for example).