@WayneSchulz - Have you considered employing SQL and ODBC? In theory, you could script a SQL Job and/or SQL Reporting to accomplish what you're asking along with a set of notifications. This is something I would normally roll up in Sage CRM to the Company Summary screen or a report within Sage CRM with a bridged view into the Sage 100 tables that @BobSosbee mentioned.
I do something similar with AR and declining accounts where I look at YOY customer revenue. If it dips below a certain threshold (say 20% lower than a prior year), it will show up on a report. You could do a similar call to the credit card's expire date that show anything the will be expiring within the next month, 3 months, etc. You could even go so far as to script an escalation rule to the AR contact at the customer as well to politely inform them their credit card is about to expire.
Then again, I'm a Sage CRM guy, so I think relative to what I would do from an integration standpoint versus a native Sage 100 perspective. :)