Sorry, no solution from me - I'm in the same boat as you. I've been after an alternative ever since my tripod snagged on a footbridge sending me onto the handlebars - the bungees then catapulting me backwards, like a scene from a cartoon. Rack's never been the same since.

I've tried putting it vertically in my pannier, but it's top-heavy, still needs bungees, and has a habit of leaning over as the feet are unsecured inside the pannier.

I did find that adding those foam leg protectors to the tripod made it easier to fasten it down.

Googling 'bicycle rack tripod' didn't return anything terribly useful, other than some other people with the same problem. Maybe you should design the world's first tripod pannier? Like a quiver for arrows, with some fastening straps. I may try this myself, and if I do I'll tell you how it goes.

Good luck avoiding that granite-bound inhospitable shore...