
3 large dogs would fit in a berlingo boot, they are like a tardis! More with the seats folded or removed, of course - I bought mine when I had 4 dogs and I've had 8 or 9 in it at a time before. If I'm dog walking I've usually got 6 in there, all big dogs. Cage at the back fits two, guard behind the front seats for the rest.
If you had crates behind crates though, access via the side doors is very restrictive unless you remove the back seats altogether: smaller cages would be easier possibly but my big cage (26" front to back) has to be right up against the front seats for me to be able to open the side door on it. It's usually at the back though.
Downside to the berlingo is aging - at least it has been with mine. Bingo is 14 next month and he's falling apart, I've had 2 major (clutch and exhaust) and 3 minor (coolant hose leak, coil spring, catalytic converter got blocked) breakdowns in the last 4 months and the front brake discs/pads still need to be done.