An air rifle to silently deal with voles and rabbit stew for dinner, that's all I have to say.
I kept my Shima Daijin in a container for about year while I was moving, but I never had any intention of growing it there so I cannot comment how would a peony perform long-term in a container. It survived being swamped by unusually heavy rains which flooded the poor-draining container though.
I think treating peonies as small fruit trees like Sandosck suggested is the key here: there are large planter designed for nursery trees (like these:
https://www.amazon.com/dp/B0815J76NY/ ) that work well. There are much better-looking ones in terracotta and similar materials but costs are literally astronomical.
The nursery owner I bought most of my peonies from says the trick for growing them in containers is to water them as little as possible: peonies are generally drought resistant and bloom before the weather really starts to heat up so it makes sense.
I also think eschewing a peat-based growing medium (whether moss peat or coco peat) for ordinary soil taken from any old field and amended as needed would held since peat is always either soggy or dry as a bone, no way in between. I grew several roses in containers over the years using ordinary soil with some added manure and they performed very well indeed: peonies are much lighter feeders than roses so they may need even less to perform well.
