Are there any racks with rear underside storage tray storage? I have used the Topeak QR Beam Rack EX Rack but the existing underside storage tray is tiny & lacks for use to stuffing in a spare tube, so does any post mounted rear racks exist that offer more storage? Or even a longer tray that can be easily fitted in the QR EX rack?

https://www.amazon.com/Topeak-Beamra...peak+post+rack