I don't understand. LSP's have an on-chain setup cost. What you are suggesting implies that this is a negligible cost which it is not.
Discussion
No. I don't suggest it is negligable. Also I am not talking about a how. It is more like a "what". Might not be possible.
I rather tried to come from a user perspective in this idea.
I think I heard a sub-utxo idea, where multiple people can create a subutxo, that can be combined together to make one utco to make onchain fees smaller. But it requires some trust I think. But this might be a direction for this idea I have here.