If you have a working solution, then by all means. It's just that I recall another buyer pulling his hair out over the same situation....trying to solve this mystery of the unknown caliper.
It is an oddball set up. And I'm sure it wasn't by error too. I guess we'll never find out unless we find one of the former Lotus management. There was a recent Lotus thread with a post of a Lotus catalog. (1st I've seen here)
Maybe your eye can spot the corresponding model to your frame? There was a parts list for each model too.