If you are solo it’s easy to do in a NAS 90. A couple is possible, but you will likely need a RTT. The limiting factor with a couple is that, unless one person is very short, you can’t make the driver’s side flat for a platform above the seats because of the steering wheel (this is easy to do on the passenger side).
Go and look at any of the D90 overland builds on YouTube and you will see lots of good ideas. The soft top does not really change the builds much (just need a full roof rack or mount a small RTT to the front cage and then you don’t get an awning.
Like this without the stuff in the top
There is plenty of room in a NAS90 for all the stuff you could want (of course it’s not secure unless in built in boxes) and one can carry a lot of weight.
And I know you don’t want a second tank, but if you need distance on fuel, that seems pretty much a requirement to me. I had a NAS 90 with a second tank (of course I never used it). Just use a transfer pump and it’s pretty simple because it’s a factory location on some ROW 90s (you can do an under seat fill if you don’t want to add a second external filler).