Mike,
Getting the nomination of three parties--particularly parties on the left--is one thing that hasn't been tried.
Certainly getting cross-endorsements from other parties would be great. In fact, the only time Libertarians have been elected to their State Congresses (in Alaska and NH) has been when they have had cross-endorsements (from the Republican Party). (Richard will correct me if I'm mistaken).
However, since California does not allow fusion candidates, this is not an option here. Consequently, I'm unclear what you're suggesting.
the one conclusion that can be drawn from our record is that nothing we do will allow us to get elected.
There's a difference between what we try to do and what we succeed at doing.
Our candidates have succeeded at watering down our positions, with little noticeable effect. However, many other projects we've tried to do we've been unsuccessful at, e.g., outspend the major party candidates, participate in national media candidate debates with the Big Govt parties, have a celebrity run as an LP candidate, be positively identified consistently in the media as spearheading a nation-wide protest or public policy position.
Best, Michael