Another thing about my question that I struggle with is that I hate using string literals all over the place, which you have to do with field IDs. At the same time, I hate the idea of creating an entire custom module just to load what might be a few field IDs. It seems like a lot of unnecessary work.

I'm wrangling this by using real types, so NS records are defined once in a strongly typed manner and naturally reused by any number of SS2 scripts via import. e.g. https://github.com/ExploreConsulting/netsuite-fasttrack-toolkit-ss2/blob/master/DataAccess/InvoiceBase.ts