We have perches the very same as that for our Indian fantails, but we keep them away from the wall at the back by 1-2 inches, when we scrape them (sorry when your Irish sister scrapes them ) the crap falls down the back onto the floor
We also have the tray type but find the Indians prefer the ones you have as there is not enough room for them to turn in the standard ones like these and Mutley's ones, good for normal pigeons