building overhead cabinets in a trailer?

I am trying to build some overhead cabinets that do not run wall to wall - one corner of them is just sort of hanging there overhead. I'm really worried about supporting the weight.
Are there any great resources for building cabinets in a camper? How do I make these things strong enough to stay overhead? I am trying to build them with 2x2 frame work, and 3/8" ply for the facing. Am I using the wrong materials?
Granted, I tend to overbuild everything, so I may just be paranoid that I can't make them as strong as I'd like to... (picture Yogi and Boo Boo bear sleeping in the cupboard).
PS - as I have posted before - this is a living space in the front of a gooseneck horse trailer. I really appreciate the help - this forum has been incredibly helpful & inspiring for this project.
Are there any great resources for building cabinets in a camper? How do I make these things strong enough to stay overhead? I am trying to build them with 2x2 frame work, and 3/8" ply for the facing. Am I using the wrong materials?
Granted, I tend to overbuild everything, so I may just be paranoid that I can't make them as strong as I'd like to... (picture Yogi and Boo Boo bear sleeping in the cupboard).
PS - as I have posted before - this is a living space in the front of a gooseneck horse trailer. I really appreciate the help - this forum has been incredibly helpful & inspiring for this project.