Next spring I will be starting a Paul Robeson tomato (black beefsteak,
climber), but...

....it will be in a 14" terracotta pot, not directly in the ground.

This gives me a headache knowing how to stake it. This year at least,
I can't put the Paul Robeson in the ground and I can't put trellis
wires on the wall. It *has* to be in the container. Apparently it can
grow up to six feet (or more in warmer climates). It is fairly cold
here in Scotland, so I am not too worried about it becoming a monster.
Also, this will be my first staked tomato so I have no prior
experience of tall tomatoes.

So - how do I stake it? I'd guess the obvious choices would include...
i) a single stake right next to the pot, lean the first vine over a
bit and stake as normal - would it sag?

ii) make a tall tripod of three stakes lashed at the top, each stake
fixed into the ground below the level for the pot but long enough to
give some decent headroom for growing - would need about 7-foot
stakes?

Please can you offer some advice. Because it's in a container, I can't
use something like a Veggie Cage (from www.tomato-cages.com).

Thanks.