Cargo room is far better than many other non-toyota trucks (e.g. discos, jeeps), but it would be nice if it was a 'tad' bigger. For example, IIRC, my BJ60 had more rear room - maybe just the different shape.
I too have a full size cage (~65lb GWP-X) in the back with the third row seats removed that sits behind a Milford barrier. The cage faces fore and aft (not across) and actually sits on top of a shelf/drawer unit I built and have secured in the rear.
The shelf (1) gives me storage space under the dog cage as it rests on top of the wheel wells (2) brings the cage up to window level to give the og a better view and access to air (3) still has some room above the cage for additional storage (light stuff like a tarp) and (4) allows a full 1/2 of the rear to be used for cargo (vs if you had to place the cage within the wheel wells).
There is also a cubby hole aft of the rear wheel well, under the shelf that I store his leash, dog treats and 4l of water. I can always access this, even whem the truck is full. Similarly, between the cage and the window there is a long space (fore and aft) where I can store other things I need to get to (eg small shovel, first aid kit, ice scraper)
If I don't have enough cargo to keep the cage in its place (it's a tight fit), I use a ratchet strap to strap the cage down.
I also designed the shelf/drawer so that I can still fit and fold down one of the rear (3rd row) seats if needed (never have, so I removed it this summer - I also call it the prisoner box as the person would be sitting behind the cargo barrier). With this set-up, I can take the entire family (3 kids) and dog to our cabin without any cargo in the passenger compartment. If i really need more space (skis, snowshoes, garden stuff, bedding) - I throw on a Thule long box.
Get the 80, you'll love it!
Cheers, Hugh
Just looked at my cage - it's a 'large' 36"L x 24"W x 26"H. The Milford barrier probably takes up 1-2", but no way you would get a 41" cage in fore and aft.