I did it that way - used 12v t socket with voltmeter from Aliexpress and wrapped all this long wire from the Qi pad on this adapter so all wire sits like coil on part of 12v adapter and barely visible , then insert in one of 12v socket QC 3.0 adapter and connected pad to QC 3.0 adapter.
This way I get fast qi charging, have voltmeter and another 12v socket
But if you mean to put QI element under plastic tray it’s also possible but that too match work to disassemble all plastic parts.