Actually you can definitely trust these pieces to take the load... and then some. A piece of wood that naturally grew into a specific shape is much strong alon

Actually you can definitely trust these pieces to take the load... and then some. A piece of wood that naturally grew into a specific shape is much strong along that shape than any kind of joinery you can come up with. This fact has long been known and exploited in whole-tree and roundwood architecture... do some image searches for those terms to see some impressive stuff.