EDIT: I'm gonna need them to clarify, because on the FAQ page it says:
Q: The rules state that you need a roll cage. Do I need a roll cage for my truck or SUV?
A: As long as the cab is as it was originally and you have seat belts and
no back seat passengers.
No way am I putting my 5-year-old in the front seat with me. Man, she'll be really disappointed if the park won't let her in!
EDIT #2: After reading the FAQ and rules again,
I'm willing to bet that backseat passengers are permitted as long as they have seat belts and are protected by a structurally sound SUV roof or Jeep rollbar. (In other words, no kids in the back up a pickup bed covered by a fiberglass camper shell.) I will call Badlands anyway, to see if I need to get my daughter's paperwork notarized before I arrive or if they have a notary public. It's bad enough I have to pay $15 for her as a passenger. I thought passengers were only $5...
Their map needs work. It's pretty useless. Looks like someone spilled coffee on it, grew mold on it, and then scanned it.

Can't they color code the actual trails? The Red, Green, and Orange Trail dots aren't telling me much. Are those the trailheads? Looks the like Orange Trail is the only trail with an entrance (at least it has the word "entrance"), and the Green Trail starts on a road. I'm confused.
Yes that rule about roll bars only applys to something with a removable top. If your in a SUV you are fine. passengers are only 5 dollars. The 15 dollars is for if they are driving something like a quad. And almost every off road park ive been to has had pretty crappy maps but atleast it give you a idea. I think i remeber Don having his kid in the back seat last time we were out.