I used to commute regularly on UPS from DFW to SJU. Those guys/gals are friggin fantastic! There is more than enough accomadations for sleeping, computering, and eating in the Ops building. Depending on where you are going from/to....you will only have 4-6 hrs at the most in SDF. The flight from DFW got in around 1230ish and I took off for SJU at 0430ish. If my feable memory serves me correctly

They put a crew meal on board for you as a jumpseater.....you can't even get a smile out of a AA, UA, DA, WN, etc employee.....more less a crew meal. UPS was a dream to commute on.

As for the getting back and forth....I was fortunate to have the wife drop off/pick up in DFW and the Eagle or UPS Ramp Sups would pick me up in SJU.

Good Luck!