Inverse Kinematics Aiming

I’m making a machine gun where the player can manouvre it on the axes shown below.

I need the player’s hands to be on the handles and walk around the gun as it moves. The head should be looking down the sights, so the torso and legs need to bend if the gun is pointed up or down. Here is an example similar to what I am trying to achieve: Grand Piece Online - Cannon Aim (Youtube)

So far I’ve tried a few solutions:

  1. Roblox IKController:
    These really didn’t work because you can’t have multiple end effectors with them. It works fine if I was only moving the arms, but I need the whole body to work together for this to work.

  2. EgoMoose’s FABRIK Module:
    I think this may be the way to go about it, but it is really quite difficult and I am stuck on where to go next. I tried making a chain for the body like so:


    However, the body does really weird things like bend backwards and I’m not sure what to do to make it more realistic. Furthermore, I need to know where to plant the feet when moving.

Thanks for taking the time to read - I appreciate the help!