CautionToTheWind: "I like the design style of a fold-up. One down side, for me, wouldn't have a super comfortable bed (my hybrid at home is hard to beat). So a hybrid style bed must lay flat. Bed is sooo important for a restful sleep."
Right!
Unfortunately, many people who build things like folding beds simply don't think the design through completely, and then they have to 'adjust' the arrangement by using a cheap, thin mattress, and comfort goes out the window.
If you go to Google Images and look for folding beds for a van, you will see the same design 99 times out of 100: They measure the WIDTH of the mattress, make a platform exactly that wide, attach it with hinges to fixed parts of the wall of the van; then they realize they didn't leave room for the THICKNESS of the mattress. So they find a thin piece of foam that they can squash against the wall of the van and call it good. I don't call that 'good', I call that 'sloppy'.
Someone on this site posted a good drawing of how it needs to be, but I can't find it because the internal search engine will only seems to search for single words. If someone could post the picture or the link, that would be wonderful.
But if you look at this make-do photo:
https://s-media-cache-ak0.pinimg.com/736x/92/df/17/92df175a102fd90afe8dbebdd967a6c0.jpg you will see what looks like a 2x8" plank fastened in place directly to the wall. Mind you, this is for a table, where everything folds
down, so you would need to put the hinge on the top outer edge so the bed can
fold up. YOU
NEED THIS PLANK (even if it's made from 1/2" plywood), and it needs to be the
thickness of your mattress when it's fully made up (minus pillows). Most twin mattresses are 38" wide, and the thickness can range from 5" to 20", so you'll have to measure your own, and make that solid piece at least the thickness of your mattress.
And then you make the actual platform, which is the same width as the mattress. If you have a twin mattress that is 38" wide and 7" thick, the total distance from the inner wall of the van to the edge of the bed would be 42", minimum, NOT 38".
When you fold down the bed, you will have a little shelf on the wall side. And don't plan to fill that portion of the wall with hooks or shelves. It is strictly for the mattress.