There is a modified version of bremen called bremen_truckmod that I believe it's the same as bremen_final but with destroyable truck. In the mapscript you can put more health to the truck so it's more difficult to be damaged. I believe if you manage to play with globalaccums you can set a different health for each part of the truck run (maybe set 9999 health at beginning, 2000 after barrier 1 and 1050 or less after barrier 2)
But my guess is that from bremen_final you can't make destroyable truck, at least I tried it and I couldn't find the way. I guess the model properties have to be changed in the map itself and can't be modified by mapscript, or I guess I don't know enough scripting
Same for CP, it's the neutral cp used, so both teams can build it. Unless you try removing all the script for axis CP, and it stays with the neutral model but only allies can build it... You could try and see
Goldrush: in my experience if you are engineer you have to take it easy otherwise you'll be bald at a young age, if you manage to get past all the enemy flamer, nades, landmines, mortar.... you'll get the final hit of your death by friendly arty, flamer, bazooka, thompson.... Even if you have a strong team and manage to steal both golds, there is a high chance for axis to stop it (engi can sneak and make second barrier, they can spam nades to truck, landmines...)
About supply depot: how many times do allies capture flag before destroying main gate? It's way easiser to plant dyna down and let the script capture the spawn for you that trying to capture...
Maps are biased for defending team in servers like teammuppet with high amount of players, all you have to do is wait and click as defender, the choke points are 99% for attacking team (Caen2 for axis is RIP....)
So in the end, the best option will be to enforce defending players to play some time in attacking teams (and disabling mortar, always )