I have a dual cab ute and my car seat has to go a bit more upright than I thought it would. I bought an extra newborn insert to help her head stay supported being a bit more upright for those first few months.
Someone told me that the back of the car seat shouldn't touch the back of the car seat and there should be a gap. No way could we ever have that the passenger seat would be in the glove box. I have a safe and sound something or other lol can't remember which one ...
haha, yep no way could we leave a gap! I don't even think a 4X4 could leave a gap!

Have you tried putting it in the middle? That's usually the safest spot for them anyway, and means that it doesn't matter if your driver or passenger you can still see and reach baby. I tried all 3 spots and found the middle easiest by far when rear facing. Make sure you and your dh watch closely when you get it checked for proper install, you'll need to know how to do it properly yourself too.
I think the seat may be too wide. But we will check tomorrow