Personally, I’d just upload the theme and then duplicate the widgets on the remote site. It’s far less hassle than try to move a whole site.
I do this kind of theme development/uploading all the time and it’s actually a lot easier than it sounds. One thing I would suggest, however – get friendly with the remote site’s error logs. If you’ve introduced a new function in the theme, there’s an outside chance that, as the remote server environment won’t match your local one exactly, what works locally doesn’t work quite the same elsewhere. But that really doesn’t happen very often.
