You might be able to crop a bit from the top.
Not much of a critique, but I did want to say that I saw the PBS show on Plitvice National Park, and it look incredibly beautiful. Are you aware of any photo tours/guides that might be available?
Excuse me I dont quite understand, you are interested in a book/monography about the lakes or in getting a guided tour on the spot?
As fo the books I saw them in the park to buy, you should find them on the net i guess
I can tell you for a fact that there are organised tours around the park but it's much more fun to discover things yourself.
I think it is allowed to take any kind of photo gear inside without restrictions or paying any kind of royalties to the administration. I took in oly 8080, but I saw numerous people with canons 5d,1d,nikons with tele lens and large bags of equipment.
Hope this helps
p.s You wouldn't believe how beautiful it is, I surely didnt expect it to be so good. Must go back in winter when everything will be frozen!