The troupe style play from Ars Magica would help address the different pacing from kingdom building to adventuring.
http://www.redcap.org/page/Troupe_style
Basically the players would have a couple characters and would assemble a team together for an adventure from their pool, the other characters would be attending to business as usual. In Ars Magica the focus of play can become the covenant (mage tower, town, townsfolk, etc) where everyone lives. Every player has a Magi, Companion (highly skilled person), and can draw from a pool of Grogs (grunt warriors) for the mission.
Magi often want to stay in their labs/libraries (and are considered to be 'in charge' of the covenant) so normally only one or two go out on an adventure. Companions are often specialists of some sort so are only suitable to some adventures. Grogs are the rank and file warriors and each player might bring more than one. The 'kingdom level' adventures in Ars Magic would be based on lab/library work, deciding covenant issues, and engaging in politics. Many of these things are based on seasons of time.
Now this wouldn't address at all the issues with RPOL time making the adventure run six real life months before you can get back to running the kingdom.