I am trying to create hot wallets using the lightning network but I don't want to create a new node for each user. Is there a way to have multiple users be able to use a single lnd node?
Yes absolutely. Many users can use / share one lightning node. You might have to create some accounting sodtware if you want every user to have their own funds. This is a classical custodial wallet solution. I am not aware of open source solutions but I build one on top of the clightning api. This solution should work in a. Very similar way for lnd.
Start by looking at the grpc api and macaroons so that you can create such a software on top of your lightning node