You might be able to fit the ladder through the middle of the rear seat and between the front seats, and still be able to close the tailgate without the ladder touching the dash. I would measure it first though.
But my advice is not to buy an 8 foot ladder in the first place. I have one and I never use it. It's an inconvenient size that is difficult to use indoors (and next to impossible in rooms with 8 foot ceilings) but too short for a lot of outdoor jobs. The ladders I use the most are an old wooden 6 foot step ladder, and a couple of 17 foot telescoping multi-purpose ladders. Multi-purpose ladders are heavy, but convenient as hell. I also have a 32 foot extension ladder for the high stuff. I would start with a 6 foot step ladder and a medium-sized multi-purpose ladder and go from there.