Mary Stella, I did one a couple of years ago, but mine is probably 6 x 8 ft
I am interplanting peonies with other plants though. Generally it is worth it and I am thinking about making new ones - may be one every few years - a lot of work involved. However I should switch from wooden beams to concrete traffic curbs - if I can find one. I saw someone doing it and I think it is great as long it is not very heavy to move...
Nick, your peonies look great and far ahead than what we have in Toronto.