T14 is a coward dog...
I have to say that I have won sometimes that mission without any MBT or Ramka like tank in the party, but when you see the MBTs going very fast to the sniper positions on the hill at the beginning of the match you probably know in advance that the game is lost.
In such situation I had maybe won only one time, at least I can remember only it, but I was in a Murder, not in a Mephisto, and I had Erin as commander, I went to spot, was killed after some time, but i did respawn and the other squishy ones followed my example and made their part, I was lucky that was good players, then finally even the cowards in MBT joined to the party to help cap the town, when most of the work had been already done by us squishy, and at least was in the right place when we had to defend it.
But it is the only time i can remember, way better to be 5 with no armor but the will to fight and at least some part of the brain working then having a couple of MBT snipers, that in your case was not even good at that...