I timed out while editting. Use the following "Scott" drawing. 12 lead generator drawings
Basically it is a open delta where Phases A & B are connected in opposing series and Phase C is connected in aiding series to the combined A & B. The output "L1"is connected to the free end of A, the "neutral" is the connection between B & C, and "L2" is the free end of C. The connection between A & B is not used.
This limits the unit's maximum power to 2/3 of full rating but is does load the 3 phase input equally.