Design choice and max weight+bending for cantilever

Question

I am playing around with designing a truck camper with overhanging/cabover sleeping area/bed (picture).
The sleeping area/bed will be supported by 3 2x4s.
Now I need to figure out the best design and if they are actually feasible.

Design 1:

All 3 2x4 are cantilevers resting on 2x4 coming up from the bottom.

The view from the top:

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View from the side:

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Design 2:

The middle 2x4 is a cantilevers resting on 2x4 coming up from the bottom.
The 2x4 on the sides are longer and resting on 2 2x4s

The view from the top:

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View from the side:

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The dimensions

The cantilevers are 72" long. For Design 2 I will have an extra of 36" coming to the 2nd 2x4.

The weight on the 3 bars will be around 440lbl. This excludes any movement which might add stress to the structure.

The questions

1. Is this feasible at all?
2. Can any of the 2 designs carry the weight?
3. If possible could I come by with 2x2 to save weight?

Also I would greatly appreciate any reading material on how I can calculating this.

Answer 1

Design 1 does not look like a cantilever design. It looks like the ends of the boards are attached to vertical posts. No, I don’t think this design will work.

In Design 2, the two outside boards look like a cantilever, but the middle board looks like the end of the board is attached to something, but I’m not sure how it’s attached.

You could use a couple of 2x4’s (on edge) for a 6’ cantilever to support about 220 lbs. (half of total estimated weight) but how the connections are made are critical.

I’d use the vertical sheathing to stiffen the cantilever, but again, how it’s all connected is critical.

BTW, I doubt if your total load is just 440 lbs. (Total load includes “live load” plus “dead load”.) Also, as you suggest, movement will cause the cantilever to bounce and put extra stress on the supports.