Child Car Seat suggestions or after market LATCH system kit

I have a 2000 Intrepid. I am in the market for a convertible car seat that is easy to secure in my car without the LATCH system. I can't seem to get the car seat to feel really secure with just the seatbelt when the car seat is in the rear facing position. My Intrepid does not have the LATCH (Lower Anchors and Tethers for CHildren) system installed. (these are the brackets that are installed where the seatbelts are anchored in between the seats. I have the tether anchors in the back window for the front facing seats.) I called the dealer to see if there was an aftermarket kit available to equip the Intrepid with the LATCH system, and they said they don't have one. Has anyone else had any luck with finding something that would work, or can anyone recommend a good convertible car seat that I could use for a few more months in the rear facing position that is easier to inatall using just the seatbelt? The seat I currently have is one that you have to thread the seatbelt underneath the pad in the carseat. It is almost impossible to get the seatbelt to tighten when you are trying to pull the strap from underneath the padding on the car seat. I would welcome some advise from others that have overcome this problem.

Thanks!
Rumpleteazeramk@hotmail.com