Dogs on Metro

Hey all, I'm about to move to the midtown/montrose area after living in the greater Houston area for the past couple of years. I would like to take the bus or rail sometimes to go to places I don't want to drive and park at like beer gardens, events, etc. I also like bringing my dog to these types of things when they are pet friendly. Metro's official policy is

Customers can carry a pet on the bus and the rail as long as it is caged properly.

He's about 25 pounds and is 28" long by 20" tall, so he doesn't fit in a soft travel carrier. My question is, can I take him in something like one of these dog backpacks on the metro? example Or does anyone have any other suggestions?