I never build a Schwerer on the front lines (unless I am already stomping). This salty thread or whatever you want to call it is coming off of a game where I built the schwerer back at the cutoff for Rails and Metal just like you say. As soon as it was noticed, it was destroyed about 20 seconds later, just before my first tank was out. It wasn't long before I was dead as my teammate could not take up the slack.
Of course the opponents teased me that I shouldn't build a forward base then. And hence this thread.
North or south spawn ? Left or right side? How was it destroyed? By units or offmap ? IF you don't have a pocket healing HQ, a map small enough to have the Schwerer protected by at least one of the players at all times or if you are not spawned on the "defensive" side of a 2v2 map, you put it on the base.
Rails and Metals force the players bases to be divided, which makes retreating leaving a side really vulnerable.
On teamgames, value of forward truck lose value as they can be focus fired by 2 or more players units and offmaps.