Welcome to the Nissan Patrol forum. To post a question and to see less adds on the forum then you will have to register
first. We are an easy going friendly forum so join in the conversations and feel free to ask any questions.
Become a forum sponsor for only $20 and see no adds with faster page loading times and many extras benefits.
It all depends on what sort of offroading you're going to be doing. I've got a 2" suspension lift and run on 33" rubber and play pretty hard in it and for the most part certainly does the job. You can probably get away with not having to do any other work to it if you stick to 2".
In regards to carrying an 80kg on the roof (hope I read your post right), your roof is only rated to carry approx 100 or 110kg, so also factor in the weight of your roof rack, you'll be pretty close to your max load..... And before anyone pipes in, yes there are alot of folk who carry alot more weight. But I like to err on the side of caution. Plus it will be crap for your centre of gravity.