Corniceman,
a couple of friends have done this recently - both strong and fit guys
one did the 7 in 3 hours ( I guess from the top car park )
the other did the 8 in 5:25 having a fair bit of snow cover to contend with.
you're maybe looking at a 3rd of a BG - so perhaps a quarter of the time to get round it - 6 hours (given you shouldn't have any snow on the ground by July ) ?