FWIW, I use a 30" folding crate when I do PnP missions.
I'm able to load & open the crate once positioned in the rear baggage area of my 7. I've cut out the crate top section & lined the rough edges with vinyl tubing. This enables me to top load dogs up to about 25 lbs.
Danny "RoadRunner" Landry
Morphed RV7(formally 7A), N20DL, PnP Pilot