Jane -
Understand the reasons for doing your trip around your birthday, but weather will be very unpredictable, and near impossible in some of the areas of best scenery.
I met a bloke last summer that was doing4 or 5 weeks in the western US - it was on a harley and he's a harley rider at home, but I probably could put him in touch with you - he's in the New Forest area I believe.
Also, NOBBY, here on this board (he's from over there) did a round the US tour - bought a Triumph here and rode for months, I don't recall what he did with the BA when he left, I know another member here stored it briefly for him.
Anyway, keep us in the loop as you plan - I am sure there are some that would be more than willing to meet up with you on your travels depending on schedules and such!
Take care!
Becky