a hotel in Munich? which one?
I bring my dog to hotels all the time. I don't know what a Dackel is, but I'm guessing it's larger than my chihuahua. Why doesn't your vet want you to board her? Won't she have similar issues at the hotel that he's worried she might at a kennel?
In any event, you can also shut her up in the bathroom. If she's familiar with the cage though, that will be better and less stressful for her. If I leave my dog in the room (which I try not to do of course) I usually put a do not disturb on the door, so the maids don't try and come in. Also, I might suggest requesting a room as far away from the elevator and the maid closet as possible - hearing people walk by outside your hotel room door frequently can also be stressful, whether you are there with her or not. I also usually leave the TV-stimulation as well as covers some noise...