The trick about having somewhere to hide is also having two or more exits. If you had themin a smaller area with a hidey-box andthey both ended up in thebox, thenthey're more inclined than ever'argue' about the space.
Can you just bunny-proof a whole room and let them in it for at least a few hours? They'll be busy exploring, maybe together, maybe not, but you'll see if they're aggressive when they simply cross each others' paths. (I don't think they will be, and if one bunny is, the other one can simply run off). And the true test will come at the end of their exploring time whether they cuddle up together.
I don't think time together in a small area is much different than putting them in a cage together, they're bound to be a little more cranky. They don't have much to do other than confront each other.
sas