Harknott and Wrynose, as has been sais before, don't do it in anything bigger than a panel van, personally I wouldn't even do it in my T4. Not that I don't think the vehicle is capable, more the vehicles comming the other way. Those bends are very steep on the corners.
I once heard of an american tourist who moaned that they never saw any rhinoceros when they went over the pass !
Honister, not as bad as Hardknott, narrow in places, I have taken my T4 over here in absolutley atrocious weather, the rain was running down the road like a River, the van tyres were strugling for grip on the way up, if I has stopped it felt like I wouldnt have been able to pull away again, but as I said the water running down the road was incredible. I was well pleased with the T4s performance on that day.
I have seen larger campers try this and cause many problems for other users, my advice is dont try it in anything larger than a panel van.
Hope this helps.