I'd try sleepers that are like the gowns before I'd try any kind of bumper.
As to the question of safety, Moon explains that young babies (for whom bumpers are designed, given that many carry a warning suggesting that they be removed from the crib once a baby can pull himself to standing) don't have the muscle strength or coordination to fling themselves across the crib hard enough to really injure themselves. Additionally, she adds, while it is possible for a baby to get an arm or a leg stuck between crib slats, it's virtually impossible to break a limb by doing so—which means that at most, the experience will be uncomfortable and upsetting, but not life-threatening, until a caregiver arrives to help.
Bumper Alternatives: Are They Safe?
As an alternative to traditional crib bumpers, some parents have turned to breathable, mesh bumpers
or other bumper alternatives, but Moon said that the AAP does not suggest that parents buy them. "We're, right now, recommending nothing in the crib, because again, we don't see the point of it. So, why have something in the crib if it's not there for a reason?"