I wouldn’t associate SP with WILD at all, because you are teaching your subconscious to expect it. That’s what I, in my limited experience, have come to learn during my experiments with CANWILD.
But, as you point out, if you train yourself to lay still, and keep your eyes closed you will not experience SP, because how can you, if you do not move. You may suspect it, but not know for sure, because you did not confirm your inability to move.
During my WILD attempts, if I start to feel sensations like electricity or hear sounds, that’s my cue to stay very still. When the sensations subside, imagine yourself rolling out of bed. I only experience SP sometimes when returning to wakefulness, the same deal applies, keep your eyes firmly closed, do not move until all sounds and sensations have dissipated.