I put Jack Lilley engine bars on my TBird
Pic. May not be suitable for the TBS as they are only available in the chrome finish (I think). Fortunately, I've never had to put them to the test but they look as though they'd do a reasonable job of protecting the major components of the bike.
I don't think you can get any 'nylon bobbin' type protectors for the Thunderbirds, but you may be able modify the fittings from a set designed for something like a Bandit 1200 or similar.