For regional trains in Germany, how can I find out how long the train will be?
Background: A train I take regularly usually has six carriages in two trainsets, but sometimes it only has three carriages in one trainset. In my experience, sitting at the extreme end of a six-carriage train, it's usually quite empty and bringing a bicycle is no problem at all, so I wait at the end of the platform with my bike. When the train arrives and turns out to be half as long, I need to run to the end of the train, where so many people (likewise surprised by the short train) are entering that I feel anti-social for bringing my bicycle at all — or I might be told I can't bring it (but then it's too late to lock it and take the train without my bike).
It would be useful to know the length of the train in advance, so that I can 1) wait in a more suitable place, and 2) not bring a bicycle if the train is short.
Even without a bicycle I might want to wait at the extreme end for being in the least busy section.
I asked a staff member, who told me that one strong hint in the DB travel planner is the note Mehrere wagen fehlen, meaning multiple carriages are missing:
However, Mehrere wagen fehlen, while useful, seems to be a relative statement only. The train an hour later does not have such a message. That might mean that the train is longer, or it might mean that it is scheduled to run as a short train.
Another hint is that at some stations, the train may either be indicated as departing from Gleis 6 A-F or from Gleis 6 D-F. But I can't seem to find this information online.
Then there is the DB indicator on how busy a train is expected to be, but I've found this to be quite unreliable for regional trains.
Can I find other hints of the length that a particular train departure has today?