I am thinking about trying a potato box but I also like the idea of companion planting. I don't have a lot of space, so I would like to get as much out of my garden as possible.

Has anyone tried planting other crops in with the potatoes? Say after you stop raising the box and let the potatoes bush out? I have also thought about using the sides of the box; has anyone tried this?

Specifically I am thinking about the following:

I have read that potatoes and lentils are good companion crops. Does anyone know if it would be possible to plant lentils on the sides of a potato box (through holes or between slats) and attach a lattice or support for the beans? I realize that I may have to make the box a little bigger and keep the potatoes toward the middle to have enough room for all of the roots, but I just wasn't sure if this was even possible.