I too have a passenger seat; went with an Ultrashield 15" and I fabbed up a floor mount. It came in just under 25lbs...made a seat-back brace and camera mount, too.
I have a Ground Control E36 M front sway bar on the way this week, that might add a pound or two, we'll see. One other tidbit I found amazing - 18x10 LTWs with 285/30 V710s weigh 7lbs A PIECE less than my 17x8 Team Dynamics with 255/40 RE01-Rs...49lbs vs 42lbs.
Got the fender roller going this weekend, too. The 18x10s have more than enough room in the rear...I'll probably end up running a smallish spacer back there for the hell of it. Honestly, there's room for 315s. The front is another story. Et 43 is way too much offset, so I have some bolt-on 25mm spacers from Option on the way. I mocked everything up with 2 12mm spacers stacked up. That provided 3-4mm clearance between tire and coilover. Looks badass, too.
I had all intentions of towing to events but I've recently taken a 10% pay cut ON TOP of 32 hr work weeks...renting/buying a trailer and installing tow provisions on the x5 was first on the budget cuts. I'll whip up some sort of removable strap or tray to hold the windows up if it rains. Or it could just not rain
