This was a common event on the thunderdome server RIP. It was hilarious and fun.

Simple Idea, give 15 minutes or a set amount of build supplies at the beginning to build. The first team to take down the other wins. Leave the timer and tickets. Have some sort of explanation on the screen like admin notifications but last for the entire build time at the beginning to help the uninitiated. Of course commander assets would be disabled.

I guess also each team would have an attacking main spawn point near the enemy FOB location? I haven't thought this part through. Also the defenders would have a limited map. So the game doesn't devolve into hab hunting and main camping.

Note the thunderdome server would usually have performance problems so there is that problem. The build supply limit would help with performance/memory problems.