Even if you have enough inbound liquidity, you probably wouldn't be able to find a route. We're talking over 312.5 million sats. Typical channel sizes are a few to tens of million sats.

Also, I don't even think the protocol allows for lightning payments when solo mining. Coinbase transactions (the block reward tx, nothing to do with the exchange) are always done on chain.

I'd imagine so. I don't have anywhere near that much inbound liquidity.

Undisciplined

You don't have to worry about lightning payments if you go solo, as 3.125+block fees btc is a big fat UTXO and probably won't be able to be routed over the lightning network. If you ever solo mine a block, I think you can only receive the reward on chain.