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There are excavations of a Roman camp in Hedemünden that are thought to belong into this time frame. This is located well east of the Rhine, but not that close to the Elbe river. Some other camps from the same set of campaigns, but further to the west or southwest, are at Rödgen and Oberaden.
Another site quite to the east, but from slightly later according to coins found, is Wilkenburg near Hanover. Some maps on WP put the Wilkenburg site into the conext of Varus' campaign in 9 AD, but the German wikipedia article puts it some years earlier.
The settlement (as opposed to camp) at Waldgirmes site also belongs into roughly this timeframe.
The sites at the Harzhorn and at Hachelbich are even further to the east, but thought to belong to much later campaigns.