Your surplus idea has significant problems: First, good luck if you aren't owning a single family home, as then you aren't tax free. Second, that you can still massively speculate by buying the highest valued land you can, in the largest plot possible, and then have the best leverage. So prices of land don't go down, but way up! And that's while the land is also less useful to neighbors, as a large plot with a house in it is far worse than, say, a corner store, a park, or an office. So you are rewarding the land use that is the lowest value to neighbors, while theoretically calling that affordability.
If you want more desirable land to be available to more people, the only sensible alternative is to make more people be able to use it at a time: Anything else is just picking a different favorite way to decide who gets to use it/buy it. It also makes the land more useful in general: The bay area would be much lower balue than it is now if it was occupied by a sole proprietor who is the only one traversing its current streets and buildings.