I definitely recommend a cat tree! My bengal LOVES it, and will constantly be found on top of one playing all by himself... so cute.
I have a *very* heavy cat tree... I wish I could remember where I found it online. It is made of real wood and has a very sturdy base - very tall, too. It was worth every cent.
My other cat tree isn't as sturdy, so I kind of pinned it to the wall. Yuki used to literally jump all the way to the top of it without trying to climb, and he'd knock it over. All. The. Time. Pinning it was the only option, but it worked!
I never knew about bengals having GI problems - could someone give me some information on that? I know Yuki was having a few problems last year, although he is fine now...