I think that's a splendid idea about a webcam!and I'm going to suggest it to our main temple in LA, along with a yearly retreat. I know a Jodo priest in Australia is talking about meeting his far flung members via webcam.
I am in a similar position to the one you mentioned. I am training in Tendai while living in Sydney -although my teacher who is the only Tendai Priest in Australia lives in Brisbane (quite a distance from each other).
I do so by travelling either to Brisbane, at times my teacher has come to Sydney. We keep regular contact through email and of course the phone and for perhaps more important situations I am required to attend the Tendai Mission of Hawaii (with which we are affiliated).
I think in many ways, this idea of meeting via webcam would be a fantastic way to spread the teachings, particularly in these early stages. I think regardless of where in the West we choose to look, Tendai is not an easy path to follow due to limited access. At least in
Tendai's initial stages, that is to say until it can be made widely available, technology must and should be utilised.
In regards to the question at large, I think that long term a teacher is certainly necessary. However, I think that for the lay practitioner, if they are dedicated enough to practise Tendai 'solatarily', they have the 'ability to be' sole practitioners...having said that, from experience, it is immensely difficult and I have only truly become an 'orthodox Tendai' practitioner under the guidance of a teacher.