I've been doing the Full Band Support mission now that i have unlocked it from time to time and it is quite a good mission to do based on my calculations. The earnings have mostly been at the high end of the range unlike with the longer missions which end up at the short end of the range. So if I were to do the Full Band Support mission for 5 hours, the earnings should be higher than the County Tour.
But of course, that assumes you actually get all the missions in when the previous one is completed which is easier said than done. If you're at your screen and working on the browser it might be possible but otherwise, you're bound to have a gap in between a couple of them.
The next mission is 15 levels away which would take a month and a half or maybe longer. It does look pretty exciting though with decent earnings for only an hour.
