Building the layout for 2 transformer operation is easily possible. I would have the outside loop and the passing track at the log loader on one transformer. The yard, lower passing track and the connecting loop back to the divergent side of the turnout at the log loader would be fed from the second transformer. Whenever possible feed power to the point rather than the frog side of Gilbert turnouts. It reduces and simplifies the wiring and the need for fiber pins. All turnouts should be set to 2 train operation.
To do that put a short, about 3" long piece of track between the turnouts on each side of the outer loop. Feed transformer one power at those two points. Similarly put a short piece of straight track between the two back to back turnouts at the yard entrance and connect transformer 2 power there. That is all you need. I think you may also need fiber pins in the base post rails of the 2 inner loop tracks colored purple on the drawing.
It looks like this is optimized for counter clockwise operation. I count 8 places for uncouplers. By the way, the layout as now drawn is 60" wide so it will barely fit on a 5' wide board. Definitely too big if you add the 3" pieces of track I suggest.
