My heart goes out to you, greenleaf. I was in your shoes, and there is no question that age discrimination is a factor. When professors who are thinking of retiring are on the SC and they see someone who is only a decade or so younger, I don't think they are able to shut off their reservations about productivity, fighting the tenure battle, relating to much younger students, and so on, even if you are stellar in all those areas.
If you have any concerns whatsoever about your presentation (it doesn't sound like it, though), check out an acting class. I learned more in 4 hours from actors than I ever did in any other kind of training on presentations, and it helped my teaching immensely.
Despite verbal promises and excitement, eventually, I, too, have had to concede that an older candidate rarely has the "fit" that most SCs envision. I'm giving up the dream and finishing my last adjunct gig in a few weeks.
When it became clear that my academic career had to end or I'd have to start using the food shelf, I asked myself what I really loved about my doctoral training, what I would do if I won the lottery, and so on. I realised that there is one part of my training that I dearly love and doesn't have all the baggage of a FT academic career. I found an unrelated junior white collar job that pays decently (almost as much as a new TT hire at my university), 8-5, no weekends or nights. In my free time (imagine that!) I will be able to pursue what I did during my training and subsequent academic work that I really enjoy.
Just the thought of having a life again is wonderful. I hope you find an opportunity that allows you to work to live, free of the ego and emotional investment of an academic position, and provides a chance to do what you like best. In this brand new world, we cannot let our jobs define us as they did in past generations.
I hope I'm not writing this solely to console myself, but I think there is more oportunity away from academy than in it right now, and I wish you the best in finding it for yourself.