Greetings!
Those sliding slat beds were scrapped 70 years ago because people hated them, and the design should have never been revived. Better designs had two single pieces, sliding over/under each other, or hinged with legs under the front lip to support the extension. In the 70’s, the rock & roll hinges were created in several different styles. I tend to prefer the hinged 50’s-60’s style because both the seat back & bottom were angled for maximum comfort, and the conversion was simple, smooth, effortless, and trouble free.
How does your slide work? Is the weight on the rails?
The weight is ALWAYS on the rails, and with the length of the bed, they will tend to sag in the middle without substantial support work.
Can I just slide mine on top of the counter top you think? Or would it need some kind of construction. And something for not scratching the counter top I guess.
I would mount sturdy supports for the slideout portion to the side walls just above the countertops, or if resting on the countertops, add rubber feet or felt padding to the bottom of the bed extension to protect the countertops.
Have you given any thought to the idea that you might want to access the garage from the top, by lifting the bed? The lack of that option seems to be a major complaint.
From your layout above, I can’t quite tell your planned uses for the table, for the front seats, or from the bench behind, maybe both? Regardless, the table leg seems to be in a terribly poor location. The biggest advantage of lagun style tables is that the legs can be placed where they are out of the way. Preferably at the corner of a seat or cabinet rather than in the middle of the floor.
Does the bench behind the table have a back? Comfortable seating is often an overlooked but very important feature. Front seats tend to get uncomfortable much quicker than normal seats designed for working or lounging. We can get stuck inside our vans for days for various reasons, and comfortable seating makes those days much more enjoyable. At some point you may be working a remote job from inside your van too. Comfortable seating is just as important as a comfortable bed, since the majority of the time inside our vans is spent either seated or sleeping, so planning appropriately helps.
Cheers!
"Be the reason someone smiles today!" ~ Van_Dweller