Bit late to the party...
Long story, my girlfriend and I have just caught up with the rally in Tucuman and will be following it the rest of the way on a rented f650gs. We have been backpacking for the last few months without much access to the internet and this part of the trip was a complete surprise for me (21st birthday present from her and a heap of friends). We weren't organised enough to research bivouac entry and I only found this thread today... is there likely to be any way we can enter this or any future bivouacs to have a bit of a look? Last night we had a chat to some of the Australian riders through the fence (we are from Australia and got their attention with an "Aussie, Aussie, Aussie") and they seemed to think it was next to impossible.
I know it's probably too late but though it was worth asking. Also, if mcguyver or anyone else following would like to catch up while on the road, we are Pete and Suzie and would love to meet you!