Great to see ideas. Our 17JG came with drawers under the front and back benches. I extended the supports for those and then added some hdpe plastic runners so they slide in and out better. I am in the process of trying to find a way to support them better once they are pulled out. I have a system in place, but the plywood is too flimsy.
The legs fold up as you push the drawer back in. Not as fluid as I'd like, but I am working on that.
For the space that on the exterior wall of our U-dinnette, I have considered adding drawers there too, but you would only be able to pull them out about 10" before they hit the table supports.
Doing it this way tho, all you would need to do is cut the panel and reinforce the opening and build drawer guides.
But, under the dinette is some wasted space. I considered removing that kick-board and replacing it with shoe storage because that is huge issue here as well. You'd just have to make sure it wasn't too deep to interfere when the slide is out and the wiring behind there, but the height is about right for even high-top hiking boots. If you wanted to be fancy, you could even have a wide hinged door covering the messy shoes??
I would also LOVE to be able to build large industrial grade drawers under the bed so that duffle bags could be stored in them and then just pulled out to access as opposed to cleaning off the bed and then lifting it. But I don't know that I have the skills to do that appropriately.