It's actually easier to line a trench with good UV stabilised plastic (a single piece, NO holes except the minimum number you put in yourself, down the middle as far from the edges as you can).
Leave the plastic visible above the soil so you can watch for escapees (hence the UV). This works well for CA, but tuberous peas go deep so it's essential to lift the whole thing out every couple of years (but they aren't as difficult to eradicate anyway).
On the other hand I bulked up my CA stock in 4 & 6 litre pots and had no trouble with tuber size (except I've never seen one bigger than my little finger on any method so maybe my expectations are low).
They are shiny smooth and sooo easy to brush clean anyway - I tend to stir-fry and eat anything thicker than a pencil - delicious (and gas-free).
Cheers.