I dont think you will be able to fit it in your Navara, I have had rear quarters, rear bumper and a few other bits in the back of my L200 all together but it didnt work well and risked damage. The last thing you want is to crack or damage your new kit. Also the rear frame is pretty big just on its own. I would say go for the biggest van you can get so you aren't forcing anything in (I used a 7.5t horsebox, but that was maybe a little excessive & we have it sat there anyway!). The best guys to ask would be Kev & Warren as they will have seen what everyone has turned up in to pick up kits & how well they fitted. If you are trying to keep costs down & have a Navara, maybe hire a big box trailer, they are only cheap to hire & you would have the Navara AND the box space to go at.
Good luck with it mate!