I know this is received wisdom, but I got a really decent sized and aggressive growing clump out in under a day using an angle grinder and enthusiastic mattock-wielding.
Done similar for next door (and got a load of huge canes out of it as a bonus - I have a strange American made chainsaw disc for the angle grinder). Really not convinced it won’t rise from the dead though.
I’m sure you know this, but bamboo in pots only unless you want to budget for a JCB in a few years time.