I have a Continental Cargo single axle 12'x6' v-nose trailer with swing out rear doors and one side door. I considered purchasing a double axle but came across a great deal on this one.
Extra side vents and an enclosed pop-up vent on top were installed to ensure adequate ventilation. Additionally, cages were installed on both interior walls with a walkway in the middle. The built in cages allow the birds a little more freedom of movement and ease feeding/watering on long trips. (I know Jerry De Smidt carries a lot more birds than me just using dog crates.) Extra dog crates/kennels fit underneath the built in cages and down the walkway. The v-nose has plenty of space for a small feed bin, prep box, chairs, etc.
In 2019 I towed the trailer from Texas to The Ohio National (a 16 hour trip one way) without any issues. A double axle may be a little more stable but I'm happy with the performance of this trailer.