I am in the same situation with the a family of 4...Long distance touring with gear and dogs. Regardless of your final decision, there's always a compromise one way or the other.
Personally, I have found that our Cruisers fill up pretty fast, especially if you tote along a refrigerator AND all the kid stuff.
I went with a home built seven foot 4x4 trailer (from an 82 Hilux) behind my 1993 80 series and it works well..it doubles as 2 person all-weather sleeping space if needed....plenty of room on the trailer exterior and roof to add more supplies if needed. Especially for additional water & gas and spare tires.
The only negative draw back for me is the task of "Backing up" with the trailer in tow...it is not too hard, but can be complicated in a tight spot requiring such a maneuver.
I would personally suggest a TRAILER that you can sleep in AND haul ALL the family gear as the platform for a family of 4, plus all- terrain versatility.
Ultimately,this set-up allows the the interior of the vehicle to remain remain spacious, comfortable and fairly civilized.