I have an '02 pathfinder. No latch. Not sure how the seating compares.
As far as front to back room, I had no problems with either a Marathon/Blvd or a radian. This was behind the driver's seat. I never tried the center because I have 2 kids and both are outboard. There is no way in hell to fit them side by side. Even with 2 outboard, there is only a hand span between our two seats (currently a Blvd rfing and a Signo ffing). I don't think there is anyway to do 3 across given the install problems with the radian (see below)
The Britax seats with the tall bases install wonderfully outboard rearfacing in the car. I haven't tried outboard ffing with the Britax. Our old roundabout worked just great with center lap belt both ffing and rfing. It is was dd1 used when she was smaller. I haven't yet tried a Britax ffing outboard, but I'm sure it is fine. I have the Britax rfing behind the driver's seat and the seat has room to go all the way back. I just had to adjust the recline a bit on the driver's seat so it wasn't interfering. i don't have it tethered currently because with the driver's seat all the way back, there is not a straight line to the dring around the seat track. Not sure if yours is the same, but my seat moves all the way back every time I take the key out.
The radian however is a totally different story. The radian does not sit on a tall base, so the belt path is lower and closer to the seat of the car. The female belt stalks are way to long in this car. I don't know if it is the same in an '04 or not. Or maybe you have latch and it wouldn't matter anyways? I also did not try rfing in the center with the lap belt, only outboard with the lap/shoulder belt. We also tried both outboard positions. It is totally incompatible rfing with my vehicle due to the final location of the buckle on the edge of the belt path. I even had a tech from this board come and try it out. It was rock solid, and the driver seat could still be back all the way, just not reclined. But the buckle placement was unacceptable. It did not matter if there were no twists or 3 twists or anything in between.
We also tried it ffing for my older dd. The tech said it was ok, but not great, (with 3 twists), but it still was teetering on the edge of the belt path, and I'm not thrilled with that. Again, we did not try the center, only outboard.
Before purchasing the Blvd, I also tried a True Fit, and because it also sits lower without a tall base, I had the same problems (at least rfing outboard), and had to try something else.