Just get a strap back protector, I have a scott one, it's quite flexible so after a few weeks or wearing it I never notice it. It doesn't save my back everyday but it definitely has in the past, and I mean I really don't notice it anymore so might as well.
Id recommend getting leg protectors if you do a lot of park. Same there, I don't notice/feel it anymore, and it has saved me from that painful ass bruise when you fall on a rail/box that prevents you from skiing well for at least a few days a ton of times. Much more useful than the helmet imo (ok ok getting concussed is much worse but that happens very rarely compared to hitting your ass/leg on a rail)