Can I run a Kaspa node without --utxoindex if I only want to mine?

Yes — if your only goal is to mine to the node, you can omit the --utxoindex flag entirely. The --utxoindex flag exists specifically to support wallet operations such as checking balances and sending coins; mining does not require those features. Leaving it out reduces the work kaspad has to do, since it no longer needs to build and maintain a per-address balance cache. This matters for beginners on lower-powered hardware: if you are just pointing a miner at your own node and have no plans to manage funds through it, skipping --utxoindex keeps the node leaner.