If I had the option to lease my X5, I would've done so.
1. I would fully load a leased vehicle. Because you won't be able to modify it, it's best to have all the factory doo-dads. Possibly upgrade to the 4.8i (grab the Sports Package and 20" rims). Most dealers will allow tint (since it can be removed.
2. Unless you *KNOW* that you're going to exceed the lease mileage restrictions, the limits should be more than enough. See how much they're willing to work with you. Most dealers will allow you more miles than what they initially advertise with a slight increase in your rates. Besides, if you go over the limit, it doesn't cost much to pay the "over mileage".
Camera: Nikon D700 w/ RRS L-plate
Lenses: Nikon 14-24mm, 24-70mm f/2.8, 70-200mm f/2.8 VR1 w/ RRS foot, 105mm f/2.8 VR
Mobile Lighting: SB-900, SC-29, Lumiquest Softbox III, Manfrotto 12' lightstand, Westcott 60" conv. umbrella.
Bag: TTP Urban Disguise 50 v2
Support: Gitzo 2330 w/ RRS BH-40.