You sound a lot like us. Putting a trailer on was getting a pain, being able to throw anything big or mucky in the back is great.

Tritons are great mechanically (hence why we went for one, even our Mechanic wants one). Navara I believe has some kind of issue which will be $3k to fix when it happens.

Slim line seats would possible work, but I personally would find it awkward, but then I am used to the Commodore which does 3 seats across really well (well it did the few times we had 3 seats, certainly does 2 seats and 1 adult well)