First of all, you deserve my respect for visiting us (or even the intention) by coming over form the US!
Concerning the characters it is, like Orophil wrote, a confidence case. I have never been asked for any sheet of evidence neither.
In the last years there was a chance to rent a tent, respectively a place in a tent; I'm not sure if it will this year again, at least I suppose. But it will be about € 10,- each person and day extra. And I think there is kind of booking necessary for that.
Concerning gear there is - as far as I know - no possibillity of lending something.
If your request is also in terms of the limited baggage in the plane, you should try to take only the necessery garments with you and maybe wear the not too conspicuous parts of your gameclothing during your travel (in Germany you may go by train in full equipment
).
And I estimate that no one will be cross if you bring along a standard tent, expacially due to the fact that you arrive from the US.
It is surely enough if your tent is not too flashy (modern looking).
Looking forward to having two new guests from overseas in Brokeloh in 2012.
And please do not misinterpret my nickname. It has got nothing to do with racism.