Enough sleep space is a huge priority.
The bunk design was a process.....
I first was thinking slats like I've seen on YT, but I wasn't happy with the design.
Next up was a poorly thought out hinge design for the middle portion to fold down.
At the end, simplicity won out.
2x6s with a notch to slide in 3 2x4s. Since it's a short span, they're plenty strong enough. I stood on each one individually at 250 to test
The bottom right bunk has two plywood sheets on it. The top one will slide out to cover the span during the night and then we slide the 2x4s out during the day and slide the plywood back.
Note: I know I'll get well deserved crap for the particle board haha. A family member wanted to "help" and brought over the wood. It was very helpful overall and I didn't want to be ungracious.
It will be replaced shortly with regular plywood! Small railings will be added too for the kids safety. This was our first mock up in the bus with it.