Were getting close to finishing a year long map based campaign. It has been great fun with 10 players battling across middle-earth.
The intention is to have a grand finale where 5x1000+ point armies battle to the death. I'm a little worried about player downtime during this spectacle and woould like to hear suggestions as to how you would run this battle smoothly. Ideally 2 players should be able to move/shoot/fight at the same time to keep things moving. The gaming area will be around 96" square, maybe a little smaller to ensure fast confrontations.

These are the things we're looking into right now:
- Forced alliances
Each army has at least one ally until at least one army is broken. Allies could move/shoot/fight simultaneously, even if they are neighbours.
- Batch priorities
The winner of priority will also allow the highest scoring opposing player (i.e. the most distant army) to move at the same time IF they are not within bow range.
- Sight blocking terrain
A mountain range could block LoS and therefore allow for concurrency, but this also affects the travel distance, so I'm not too keen on this one.

Any other ideas? Has someone played like this without problems?