In SA you're 400 miles from the park headquarters. From the HQ campgrounds are from 15 to 25 miles on paved roads depending on where you go. You'll be able to do lots of paved road cruising if that appeals to you too. I'm not a cycle guy yet (may get there eventually) but I've roamed the back roads in everything from a Dodge van to a Suzuki Sidekick. Most have loose rocks so they're challenging for a cycle. Can't help you with the adventure ride (sounds like the river road that I've done in 3.5 hrs with the Sidekick).