When you say, "take the back seats OUT," do you mean fold them up and out of the way? My seats don't come completely out.twin set fits easily
push the front passenger seat all the way up with seat back forward. take the back seats out. put mattress in first, on an angle from the back of the front passenger seat to the rear corner driver's side. put box spring in next right up against mattress. close clam shells and you're good to go. there's room for headboard and frame, too.