About SAPing out of base...
You can only SAP for trips in your base.

However, you can SAP down to 65 hours, and then put your trips up on the trade board. If someone picks up a trip of yours off of the trade board, you could get down to the point that you only have a couple trips in base.

Then, you can pick up trips out of base.

So, if you live in CLT and are based in DAY, you could make it so you only have a couple of trips a month in DAY, and the rest in CLT.