Record sizes in NAV2016 vs. NAV2009

Hi all,

I'm testing an upgrade from NAV2009 to NAV2016. We have 2 addons - Lanham E-Ship and ChargeLogic EFT. Both of these addons add a number of custom fields to Table 112 "Sales Invoice Header". In addition we have about 6 of our own custom fields.
All of these fields fit within the 4000-byte limit of NAV2009.

In NAV2016, the standard NAV Table 112 adds 4 fields:

710	Document Exchange Identifier	Text	50
711	Document Exchange Status	Option	
712	Doc. Exch. Original Identifier	Text	50
720	Coupled to CRM	                Boolean	

So I would expect the length of the record to be still somewhere around 4000 bytes - perhaps a bit more. BUT, when I merged the Lanham and Chargelogic fields (and our handful of custom fields) into NAV2016, I received this error:

The active fields in a record cannot take up more than 8000 bytes. The active fields in the Sales Invoice Header table take up 8056 bytes. You must reduce the number or the length of the active fields.

So, I'm wondering how/why this record is now double the size? All the other standard NAV fields are the same size. Is it the conversion of data to Unicode that makes the same record take nearly twice the space? I'm baffled by this, especially since we are planning to add another Chargelogic addon which adds even more fields.