I would say you probably could still have fun with a pretty stock K5. Badlands is a very intense off road park, so you'll just want to take it easy. Try not to put your foot into it too much. I see that your in Lafayette so it's the closest to you. You could go and just stick to the basic areas and still have a good time. But I would recommend Haspin Acres in Laurel IN. It's probably about 3 hours South East of Lafayette however. Oh well, Badlands will still be fun.
Off topic, but I'm in West Lafayette right now, I go to Purdue, it's actually my last day here as I'm transferring down to Bloomington... Oh well, what can I say. Not really having a good time, to each his own though.