Model is getting stretched when adding Basic IK(control rig)

Currently learning on how to set up a control rig within Unreal Engine 5.4 and I am getting this weird stretching issue when I connect my basic IK. This is a simple model with a skeleton / weight paint that I created in Blender.

How it should look(before adding IK)
Before Basic IK

How it looks after I connected the basic IK
After Basic IK

Try setting all the strength ratios to 1.0? But your skin weights look a bit strange.

Still does not work. I tried to remove all the bones, re-add them inside Unreal and just make it as simple as possible by adding a few bones to the hood-part that sticks out and then re-creating a rig with basic IK but it still messes up. Bones does not have to be all straight, I mean I should be able to make organic skeletons, like an octopus for example?

Are there any good tutorials for how to create custom skeletons/rigging? Almost every tutorial or guide is using a standard human bi-ped skeleton or the Unreal skeleton.