Been a while since Iv been on here.

Just been getting back into the RE lately and looking to learn function calling using injected DLLs.
I already understand program flow and am decent at RE now like medium grade program cracking etc.
I already understand how hooking and calling remote functions works and I have done it on a few programs where I have to source code but that is where my issues arises.
When calling a function from your dll you must obv use a function prototype eg

Original function in program source


Function prototype in the DLL that I am injecting


My question is what methods do you big brain gamers use to get number of, and data type of the parameters so that you can build a function prototype without the original source code. I am currently capable of just doing a stack trace and figuring out the param if they are a simple type like and int but when data structs are passed in I get lost.

Note: I am aware that RE tools like ghidra and IDA pro attempt to do this for you. But is that seriously how the pros do it?

Thanks to any mega mind gamers that respond.