I'm not sure that it would work in the battalion scale, for that period of time. 36 v 36 easily means a lance dead a turn per side, if the dice work out and its lighter things. Just keeping reinforcements going through 12 hours would be kinda nuts. Also you do not want a player to jump in, lose all the things they're playing in 2 turns, say a 45min -1 hour, and then be out the 8 or 12 dollars that a 4 hour ticket costs for at least a turn or two. It might work at, say, regimental scale. 120 units per side, say 10 players to a side each running a company, but that point the logistics have gone insane. As has Dave for having to paint that many mechs.
I think a better option would be either 4 hour stand alone battalion fights, sorta like mini feature tables for 4-6 people per side, or 2 hour - 3 hour company level fights running as parallel ticketed events. They may have x effect on the big game, or maybe the big game determines what conditions the companies are fighting in. I dont see 2 companies being able to smash each others brains out for 4 hours in alpha strike. Then again I dont see a pair of lances doing it very well in btech, and they seem to have made that work.
/ramble