In practive, even though DL says 6-8 weeks, all of the miles have been posting almost instantly, almost at the same time as the flights post.

I'm not sure Aruba is far enough to give you enough miles. You should carefully calculate your MQM balance from all booked and anticipated business trips and then compare the needed miles to distances from BNA to possible foreign destinations using the routing and connections you would use.

If you plan to drive to BNA, fly to CVG and stay more than 24 hours, and then fly from CVG to the overseas destination (and back to BNA), be sure to check the promo rules carefully to see whether a domestic stopover is allowed on an international RT without losing all of the extra miles, including double MQMs.

An alternative would be to first fly BNA-CVG-BNA RT on one ticket and then BNA-international gateway1-foreign destination-international gateway2-BNA RT on a separate ticket for double MQMs on all DL and DL Connection flights and 5K (domestic hub) plus 25K/50K (international RT) extra bonus miles. However, BNA-CVG-BNA isn't likely to be cheap if purchased now for Thanksgiving unless you find unpopular times and connections.