how can I properly setup a multisig wallet?
That might provide a good guide:
https://coinguides.org/electrum-multisig-wallet/. It's a little complicated if the other miners haven't ever done it, before. Essentially, you all create a new wallet (seed phrase), share your master public keys and decide how many cosigners are enough to spend from the wallet; for example, 9-of-10 means that 9 signatures are required (out of 10) to spend from an address. If you all mine to one address, and you solve a block, one miner can't just take them and leave.
I think instead of complicating things with multi-sig, you should just have 10 coinbase outputs. The question remains: how will the participants verify that they're actually mining on a block template with their address included in coinbase transaction?