I just purchased a used 2008 vehicle that came with one, 1-seat in the back (the other was removed). I have a 115 pound Great Dane and I need to strap her in with a special dog car harness onto a seat that is BIG, i.e TWO SEATS that run together (like the normal back seat of a car). The harness is ONLY crash tested if she is strapped via a 3-point seat belt, all other options are dangerous for both of us (I've called several companies). So, can and how do I find a BACK SEAT that will fit into this vehicle AND that has safety belts that will work for this vehicle? Any suggestions? Thank you so much!