That is a difficult question. I guess my answer would have to be no. The reason for this is because a horse is a prey animal. No matter how trained and relaxed with you it may be, something could still startle it or scare it, and the horse may injure you totally by accident and without intending to do so.
Do I think you could train a horse to be so relaxed with you that you could snuggle with it, yes I do. With out injury? (or the potential of injury) Then no.
I personally have had horses so relaxed with me that I could sit on them while they were lying down in the pasture. Or, I could sit behind them (with their legs facing away from me, the real danger) and pet them or love on them. I have a picture of my adult daughter sitting on her mare while the mare is lying down and the mare also has a cat sitting on her back too. (my daughter is petting the cat.) But, both were ready to jump off the mare should she startle.