Find it too tight. I have 2 kids(using boosters), but if we take out one of their friends, the wife has to go in the back and place the 3rd booster in the front, not that my son complains! Also consider the space you'll need in the boot for pushchairs/prams, but you can always fit a roofbox

Also consider that for those long trips, you can hire a diesel MPV relatively cheap and save money on fuel.