Get a family cage. What's the point of keeping passengers in their seats if they get crushed when you roll?
Didn't the Geo Tracker had a small hoop type roll bar that went behind the back seat.
I think it was for mounting seat belts. It ws too low to help in a rollover.
You could also look for seats that have the seat belts built in but I guessing most would be too wide.
I can build something like that... Who wants to be a guinea pig?Photos of seat and belts......
Cani see a couple pics of that tracker seat?
New from WH. Might save you a few bucks if it will adapt to your existing roll bar.
http://www.wildhorses4x4.com/product/Rear_Weld-In_Cage_Kit/newproducts-EB#