I have now received the borax. Spent all day yesterday cutting the pieces into sizes I can actually handle on my own, then planing the sides more or less flat. Produced half a dozen large bags full of shavings for my wife.
In order to split some of the big pieces down the middle, I made myself a simple jig to hold them upright, so I could work with the chainsaw without any danger of losing control. Discovered more beautiful grain. The third image is from a piece just approaching a major crotch in the tree, and the fourth one shows a bowl blank with some nice ripple and (believe it or not) literally green wood!!! Never seen anything like it before.
All the slabs have now been treated with a 5% solution and are stacked and stickered in the garage. Even though I cut a lot of the useless parts off and lost a lot to the splitting process, the stack is still man high.