I would house them together if you have breeding plans in their future..they need to get to "know" each other. Do watch out if any are intimidated by the others during feeding time..some will be reluctant in the presence of others in a group setting. Vertical orientation isn't as important as overall space. a 4'x4'x3'high served my trio well. I would also change bedding..looks like pine or aspen in your cage thats pictured? orchid bark or cypress will work much better as you'll need to spray heavily and frequently to induce breeding...the former types of bedding may gel up if kept wet on a frequent basis.
Bill