After a couple cups of coffee, I think there may be a way to do it without an additional relay or 022 switch. You could rely of the 14-16 Volts fixed as the track voltage when traveling westbound. Depending on the length/location of the isolated section within the straightaway, the fixed voltage might provide a little increase in speed, but might not be all that different from your track voltage anyway.
I added yellow wire from left 022 to right 022 to always switch the 022 on the right to curve. Then I added blue wire from right 022 to insulated section to provide power to center rail when traveling westward. You might have to experiment a bit to use the correct binding 022 posts, but the concept is what I'm trying to depict below.
When Train travels on left loop, control rail triggers binding post and signal travels down yellow wire that changes right 022 position to curve and does not send power back to insulated section via added blue wire. Train stops at signal, then proceeds to loop on right. As train completes the loop back to 022 on the right, the control rail changes 022 to straight and fixed voltage is sent from 022 to insulated section via blue wire at bottom. Train travels straightaway without interruption, enters left loop and starts cycle again.