Would it be possible for a custom list field for a custom record to show something else / more than the ID or name? We would like to add more values to make it easier for the user to select the correct custom record value

Could make the name field contain the info you want to display... but that's pretty hackey. What I've done in similar cases was a popup to display a suitelet to pick it and then push it to the field... but that was relatively intense customization

Yeh I was afraid that would be the only solution but that's not really viable in our situation. Guess that a suitelet is the only way to go.