Store a 750+ long string on AR Invoice in EBS r12

Whenever we create an AR invoice in Oracle E-Business Suite, we receive a string that exceeds 750 characters in length for that invoice. We need to store this string in EBS—either directly on the AR invoice or in a way that it can be associated with the invoice.

In similar projects for clients using Oracle Fusion, we used a custom object to store this long string. However, in EBS R12:

1. There is no equivalent "custom object" functionality available.

2. Descriptive Flexfields (DFFs) have a maximum character limitation and cannot accommodate a 750+ character string.

Is there a way to do that? We also need to be able to extract the string and associate it to the invoice using SQL.