Hi Paul and welcome to the forums .

The 2 tier hutch would be fine , for the mini lops , if your worried and can afford the little extra and you want them to have a little more space you could always place the hutch inside a sercure box high enough so they can't jump over it , its easy to make one a few bits of wood and hinge them together so you can easily fold up for storage when you let them out and about, but The hutch would be fine , afterall this is the size most people keep a rabbit in ,, in as well as out.
As long as they get plenty of exercise when you can then I can't see any probs
Hope I helped you

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