Hi there,
when i was pregnant with son #2 he went breech, and i think at about 38 weeks i went in to hospital for the afternoon to have him turned - they use muscle relaxants and entonox gas for any discomfort, and it was a breeze! They successfully turned him.
HOWEVER, little stinker turned back and after 12 hours labor at 5 days overdue, they suddenly said "oh we think he's breech again!" and whisked me in for a c-section (i'd had one before so they wouldn't risk breech birth)
He ended up being 10lb 2oz so part of me was kinda grateful

but my 2 points are i guess, Firstly have you considered this turning procedure? it's very safe... and Secondly, why would they not try to deliver the baby breech? it sounds like you've had successful births before? I sure wish doctors would do more training on breech births these days!
Oh and finally, i was about 250lb by the time i had #2... not as big, but still an issue for the doctors (much more than it was for me, actually!)
Good luck, i hope you can get the birth you want!
Polly xx