A lengthy title no doubt, but basically I'm suggesting that the amount of tickets you have versus the amount of tickets of who you attack should be proportional to how many people can sign up and fight for you (or the other side).
For example, if I have 1000 troops (tickets) and another person has 500 troops, then I should be able to have twice as many people on my side of the battle as they can. So basically it would work like single player battles do and have a ratio depending on how much larger an army is that translates into how many people can fight for you in battle.
Maybe not have it directly proportional (where twice the tickets gets you twice as many people in game), but when it's 1000 vs 500 it shouldn't be 75 vs 75 in game. Maybe something like 90 to 60 (100 to 50 would be proportional).