Edit: And I forgot to say welcome to LD4al
The HI aren’t actually a requirement, they’re just basically a dream slowly forming around you. I do know of several people who don’t get them, so I wouldn’t let it discourage you. The biggest thing is to just stay passively focused until the dream happens. HI, SP, jolts, jerks… they’re all just side effects. As long as you ultimately get a dream in the end, that’s all that matters. If you do feel that it is negatively affecting the way you WILD, then you might want to switch to VILD where you imagine the same dream scene over and over.
As far as I’m aware neither is more difficult than the other. I know I have an easier time with VILD, and several other people claim the same. Then again, others claim the reverse. It’s only difficult if you make it difficult.