Hardy fuchsia?

I agree about the hawkshead being a bit more delicate but it's pretty enough to give it a go. Mine would do much better if I didn't neglect it.

 

Some larger flowered hardy varieties that have been reliable in either my garden or my parents' (Sheffield) in the ground are Phyllis, Display, Beacon, Margaret and the aforementioned Mrs Popple, but they die back further in most winters than the magellanica types and are hard pruned in spring so if you want permanent height they might not work. Although as you are "down south" it might be milder and they might not die back as far.

 

I have that one and when I purchased it, it was called Flashlight, but this was back in 2000 and I don't think they label it that anymore. It is very easy-going and will seed around.

 

@Fat Controller it can get very big if you don't prune it.

 

I think 2ft diameter (and presumably similar depth or not much less) would be OK for a fuchsia as long as it gets watered in the growing season. They grow easily from cuttings so you could always replace it if it gets too pot-bound and starts to struggle. Top growth size shouldn't be an issue because you can prune them as hard as you like every spring, up to (or rather, down to) soil level if you like.