I know a 13 inch willn ot fit between the seats of a Dodge Caravan. Been there , tried that. We bought a 9 inch TV/VCR and used a wedge that Target sells that had Velcro. It hold it secure for normal driving byt I doubt would be safe in a crash. anyway.... I found that having the TV between the seats Didn't work well for us. I bought a system online that has 2 five inch screens that attach to the back of the seat. The VCR/TV tuner is the size of a home VCR and for now we have it in the floor board between the 2 middle seats. Eventually We will move it to better spot, behind one of the 2nd row seats, standing on end.
A quicker and cheaper option to this is the Steel Horse version of hte TV in a bag. AS far as I know it is the only one that has the screens that are not attached to the VCP. This way you can hang the bag where it will be out of the way, and strap the screen to the head rest. You can also buy extra screens for it.