Having played (well) over 1000 hours of Renegade since 2002, i can tell you that convincing public players to do just about anything is nearly impossible. Nonetheless stand against a team with a disadvantage when they can simply call it quits and move onto the next map without penalty. Several Renegade marathon servers had a !poll gameover command that was able to be initiated after 30-60+ minutes. Both teams got to vote and it needed something like 75% to pass. The satisfaction of winning is largely diminished by winning vs a surrender as well. It's a good option to have to fall back on, but it should not be treated as a "we have a disadvantage, surrender immediately" command like it is now. There should at the very least be incentive not to.
I would like to see a medal / achievements script, personally. Having "Comeback medals" be a thing where a team that was down at least 1 building at any time in the game ended up winning the game would be a nice incentive and neat overall.
Id played some old ren games that took hours .i dont remember my top longuest one playing a marathon but I guest iwas over 7 hours ..
Its not something I want to do again but fk it was a good experience no other game could do.
I like your idea having kind od reward for the comebacks.
What also can be done is Special drops after X time minutes of play to the losing team, not too much but just enought to be a good reason to hold till that time to try something else before surrending .