Quite a few people (including myself) highlighted the disconnection from the rest of the game as the main issue with powerplay on the first day of the 1.3 beta. Personally I think the simplest way around this now would be to have the powerplay faction spawn a related minor faction in each of their controlled and exploited systems. This would enable you to actually, fully take over enemy/neutral systems using the pre 1.3 mechanics. These factions would give out missions (which could have additional powerplay related flavour and rewards) and you could get benefits for the minor faction being the controlling faction of a system (such as reduced overheads), this would also give another way to undermine a faction by pushing a non-aligned minor faction etc.