You can make multiple combinations.
Having a public node (as the face node) with public channels and all liquidity shit, offering good routes. More as a decoy node.

Then behind this one, you could run another node, but only with a big private channel with your node A (public). Optional you could open another big private channel (for more reliability) with another good big node.

Then your "customers" bank will connect with private channels and nodes (like Zeus, Blixt, Breez, Electrum, Mutiny) towards your node B (private) offering them liquidity.
But for private nodes is also recommended to have 2-3 channels not just one, for more reliability and also using MPP (multi-part payment).