I'm trying to see if there's a way to have Lightspeed auto calculate how many shares to buy based on a set risk per trade %.
Sorry, but no. What you are talking about requires you to code it. We offer a number of prebuilt hotkeys and the availability to create a custom one with these parameters.
It was not my intent to do that. The software is very configurable. That said, there are certain trading requirements that can't be met by the software terminal and require programming your server to do that and send your order through an API.
"You can only customize it with the parameters available, not to whatever you want." It was memorable even if unintended.