One think to note is that if you use cryogenic proplants for your lander or lunar tug, you might face issues with fuel and oxidizer boiling off over time (unless you go for very good isolation or use active cooling, both rather heavy), reducing your time window to have everything launched & used.

You can opt for hypergolic propellants that won't boil off, but you sacrifice performance and make ground handling more expensive and dangerous due to these being highly toxic.