Really like your idea of having the orange tan leather for the dash and door toppers contrasting with the black everything else - not seen that before so I'm looking forward to seeing photos when it's all done

I think an orange tan bonnet strap would look great to match

My suggestion for what it's worth is to not go for a factory fit tonneau cover and go to those very nice chaps at Morgan Park (or other trimming establishment) and commission a 3 zip tonneau cover, especially as you want to drive it sans screens and hood in the wet .
The extra zip and side panel it creates to your outside will help keep the wind and rain out and off those nice orange tan leather toppers and protect your cockpit to a greater extent

Morgan Park have also just brought out a folding windscreen bracket for your car and they are taking orders for them in black as Kevfitz has just ordered some

That would look top banana with some aeroscreens

2008 XXVII Platform, Bugatti Blue Roadster 4 Seater