I am 99.99% sure that the
Marathon will fit in the Tahoe. I have a 2003 Tahoe. I can fit 2
Regents and squeeze a
RFing Scenera in the middle.
It is okay to have the carseat touching, as long as they are independently installed--meaning, they are not relying on the carseat next to them to be installed tightly.
I'm not sure with the Tribute--I don't get to see many of the newer vehicles that are not Chevy or Ford!