Unfortunately, spotting scopes, stugs, and double paks, just don't work on maps like dussledorf. That was specifically the type of map I was referring to. On other maps I have to problem with dealing with tanks of all types.
The next question I guess is how you deal with Calliopes as ostheer in a 2v2 AT where the USFs Ally actually helps defend his Calliopes for him? I had a game a few months back against Ciez and Momo and they went Calli and crom spam with arty cover on rails and metal. I went Jaeger armor and got 222 with spotting scopes for my elephant and a pwerfer. They just kept bombing us out they rushing with croms. Felt pretty hopeless...
If you are getting nailed by british mortar pits I highly recommend you to try out 2x mortars halftracks + 2x isgs. Answer arty with more arty '. This usually help a lot if you keep maintaining your arty and in the end brit will bleed and spend a lot of mp or mun to keep repairing pits. Keep in mind that ostheer Light artillery barrage will destroy pit in one go if your opponents brace ability is on cooldown.
Against calliopes there isn't much you can do. Just don't blob, just don't! And look for opportunities to flank him with your tanks if they don't have any mines set.
Don't forget that you have a riegel mine, this bad boy will backstab your opponent really hard and tank will be immobilized until it will not be fully repaired. I understand that sometimes everything just don't work but you have to use what you have and just keep trying. You can always try 17 min KT
Btw didn't I played against you in 1v1 ?