I had a seat cover made for the front seat that had 4 rifle slots on the back of the front seats as well as one right at the bottom on the front just behind your feet. If you bench seats it is a snap, if they are buckets you can't do the front one, and the rear one is a pull over on each front seat that makes a one piece rear flap with the rifle slots.
You can get the bucket seat version like the picture below, or solid like the first one. I like the solid one piece as it gets the guns out of view and you don't have to worry about casing them while travelling.
Mine looked like this but was part of the complete front seat cover.
