Sure thing - GameMaster task would be our bottleneck.
But do you realize - all process of unit moving would be quite formalised.

It is quite simple thing to divide units to their factions in unit list in scenario root. Then you need only clip and paste these strings and send them to player. Player will continue received strings with new provinces number after semicolon (old province numbers must be left for Game Master reference).
Game master would receive these edited strings back and change old numbers to new numbers. As simple as that! If this thing became to be adopted and all players will behave themselves in honourable manner - we can allow them to place new province numbers themselves, then GameMaster task will be diminished much more.
We can cut and paste from original sheet proction queue - then players themselves can point new buildings in appropriate provinces - all GameMaster task would be - just compile and present results in game saves. (I would against to sending actial scenario sheets to players. Players must see only his part of chart - not whole picture.) As simple as that.

Yep, each faction would have human player. More then that - Rebel faction would have more players - if we will get excessive players in process, - in Viking scenario we would get different guys as King of Cantware and Nord Rebels leader in the same time - both of them have their definite capitals. Rebels wouldn't have access to any special troops - only to common units.

I would recommend to start from Campaign map for standart Viking scenario, because it has less players and shorter scenario sheets.
When technology of this game would be checked and improved (I'm sure we will find a lot of bottlenecks) - we can advise this game technology to whole community. I'm sure a lot of MP guys would agree to new sort of experience.
Strictly speaking this form of game would be formalization of queue of MP-battles with predefined and diminishing (in case of bloody losses) or raising (as result of sound economy decisions) - arrays of usable troops.
No more - no less.