In my opinion: wrong car for such accessories
The x5 is just a softroader (no reduction, no locks, ...) - I know it may perform better offroad than most people expect (using right tyres, ...) but it's not designed for this purpose.

If you would like to have more light in some circumstances: BMW offered a xenon replacement for the front fog lights of the e39 (63130149369) & e46 (63130152441) which where activated together with the high beam. Maybe they are useable on the e53?