Custom Record or extend existing records?

I have two entities that I need to model in NetSuite:
[LIST]
[*]Physician (basically a contact with a few extra fields)
[*]Insurance Company (very basic requirements; address, contacts, name and some child records)[/LIST]I'm REALLY struggling with whether I should continue to use custom records for these entities or if I should abandon that and extend a built in record (Customer or Contact) to model physicians and ins. co.

I've found myself adding fields like:
[LIST]
[*]Address 1
[*]Address 2
[*]State
[*]Contacts (child records)
[*]Phone
[*]Fax
[*]etc[/LIST]
Obviously these are all fields that exist on the built in records.

The main reason I'm NOT using built in records is that it's very difficult to differentiate a Physician (represented by a Customer record) from a regular customer in the UI.  The same is true for Insurance Companies.  My users will be VERY confused if they try to create a new Physician and the form says "Customer".