Suitable plant for growing up obelisk/trellis in a container?

[starr]

I have a compost bin in the corner of my (small) garden and it's not especially attractive, sitting there broodingly like a grumpy dalek, so I'd like to put a couple of container plants in front of it to screen it, climbing up either an obelisk or one of those pot-sized trellis fans. I'll need to be able to move them occasionally to get to the little door at the base of the compost bin, so I was thinking I'd use plastic containers so they're not too heavy. I already have a couple of square pots 35cm across & 25cm high, that's about the widest that'll fit in the corner but I could buy taller ones if needed.
I was thinking maybe a clematis (I've got a multi blue clematis waiting to be planted) but I wasn't sure if it'd be OK in a pot this size and whether it'd grow too big. Can anyone tell me if it would need a taller pot, or recommend any other suitable plants?

[Madasafish]

We have a clematis which grows on a west facing wall in a stone trough approx 40cms longx 30 cms side x 30 cms deep.. It has done so for 20 odd years. frequent mulcjing required ... and watering in summer. - once a fortnight.

Your dimensions sound a little small...

[Sweepster]

You could consider an annual climber (though obviously that'll only give you a screen for part of the year) - sweet peas, morning glory, nasturtium? Or just go for a larger container and perhaps choose an evergreen clematis, passionflower or potato vine (both semi-evergreen) or even ivy. Bear in mind, if you get a taller plastic pot, the risk of the plant getting top-heavy when it grows and tipping over.

[starr]

I don't mind if the plant isn't evergreen, because we won't be out in the garden much in winter and you can't see the compost bin from the house, but I would like something I can plant and leave rather than having to plant something new every year.
Thanks for the suggestions so far!