Back tuck baskets are actually pretty easy. Kick doubles (or any level 5 appropriate basket) are significantly harder. On my college cheer team, I learned this first hand - we threw girls in tuck baskets that had weak tumbling on the ground and they were fine. And sometimes these baskets were LOW. Sometimes the flyer freaks out in the air the first time they try it and comes down feet first like they are doing a tuck on the ground, but even that isn’t really dangerous. I’ve never seen anyone come down head first or anything like that.