LOL, I was bored and mostly wanted to play around in Photoshop.
Arbitrarily chose DS capping on BE on SH. Imagine the reverse scenario if BE is capping on DS.
Or don't, I'm not your Mom.
1. Calculate Midpoint between Flags
2. Create round 'Capping Boundary' based on this point. (Leave enough buffer for falling behind stand for a sec).
3. Once the player hits the main meat of the capping area, exclude the area nearest to the enemy base as well (for games of 5v5 and over).
4. If the Capper leaves the Capping Area, a timer will begin counting down, just like the mission boundary does currently.
5. If the timer expires, something bad happens. (Flag Returns, Capper Explodes, PermaIFFs happen, etc).
6. If the Capper returns to the Capping Area and shortly thereafter leaves it again, the timer they previously had will resume counting down. (Maybe the timer could replenish / deplete akin to how jetting does).
7. If the Capper stays in the Capping Area, GG, GOOD BOY, PLAY AS USUAL.
I don't know that this truly helps anything besides keeping dicks from hiding in the corners, or pulling a mun and riding the edges of the map all day long to be a prick, but I feel like maybe it would help a little. :P