Polycultures in Pots - Suggestions/Ideas?

So I've got this crazy idea...  I've collected 3 4-drawer file cabinets which I plant to turn into large planters- I've removed the drawers, laid them on their backs and drilled holes for drainage.  I'm in the process of commissioning some welding work to have some material (something cool and rusty, hopefully I can find some industrial/architectural salvage in my budget!) attached for trellising or training plants.  My ultimate goal is to make use of space that was formerly paved driveway (we've depaved and laid pea gravel) and block out the not-so-scenic view of my neighbors house, a mere 20ish feet from mine.  I'll try to share some pics at some point

So here's where I'm soliciting some advice- has anyone ever attempted, had success, or failure with a mini-guild in a large container?  I'd like to try hardy kiwi in my containers, since it's a fruit we don't have yet and they apparently grow pretty well here.  Anyone grown kiwis in containers?  And as for N-fixers...could something as large as a goumi or seaberry thrive sharing a container with the kiwi?  What do y'all think?  Any other favorite perennials that will thrive in containers you'd recommend?

I grow kiwi in a container, it doesn't get much sun and suffers at the attentions of local cats- but that isn't the fault of the container!

I have successfully grown dwarf apples and cherries in large containers, I like having smaller N-fixers in the pots with the fruit trees, such as birdsfoot trefoil or clover. Also soft fruit such as gooseberry, redcurrants. Plants in pots that didn't grow well for me were mulberry and pear (pear doesn't do well in the round here either though).

I tend to use a cluster of containers rather than giant containers (just for the logistics of me moving and filling them!). So one container holds the apple tree and clover, another pot next to it holds yarrow and calendula, both the pots will include bulbs for early flowers for the bees, etc.

I've grown polyculture with some success in containers.  I think it might need to be a very big container to hold a guild.  I have lots of containers on my patio, but most hold just one or two kinds of plants;  I'm growing for yield, and sharing such a small space impacts yield too much for me.  My polyculture of tomato, chard, and calendula did pretty well last year;  but this year the calendula is outcompeting the tomato badly--and I'd prefer the tomato!  

My biggest container is the wooden base of our old sofa--so it's pretty big compared to the rest which are mostly big planters (though I've got an old laundry basket which is a good size).  It too has a polyculture with lots of little things, and everything is getting along (except another tomato!  Luckily I have one in its very own planter which is thriving).  It has a variety of vegetables and herbs and a couple random flowers.  

I have two young peach trees in containers;  one shares with some spring onions, the other with chard and nasturtium.  Neither has room for much else, though I imagine Charli's idea of a little N fixer would be better for the trees, and just have the other plants in different containers.  

Oh yeah, nearly all my containers are mini hugelkultures.  My carrot planters aren't, but I think everything else is.

Classy laundry basket planter

Sofa in foreground, peach tree against the fence

While I was reading Edible Paradise by Vera Greutink, she mentioned that she is able grow sweetcorn, climbing beans, basil, nasturtium, and a bush tomato in a container pretty well in her climate.