You are not rude. You came here for opinions and you’re getting just that. Although I have to say that gravel roads are way outside my comfort zone in more ways than one. Do you mean that gravel is likely to damage the pano roof? Will you even enjoy the difference between B&W vs HK audio over gravel roads?
Anyway, see if @BMW_Dave still has this m60 (or others?) and can do NV. Not sure if you have access to EA but this has unlimited charging as it’s a 24.
At the end of the day, it’s your money and you’ll be the one spending a lot of time in that car. Including some with your partner. Go with air or even DHP to keep both relationships happy. My $.02.