We recently purchased a bike trailer so we can go on some family bike rides around the neighborhood with our 15 month old and our 4 year old. For our 4 year old, we have a hard shell helmet which is more flat towards the back so it works really well with the trailer. For our 15 month old, we are having trouble finding a helmet that will fit her properly without sliding forward and covering her face. We have tried a bell helmet, and a giro me2 helmet. Neither of which worked very well. We are looking for helmet that is a similar style as the hardshell but isn't as heavy. Or we've heard of people putting pillows behind the child to sit them more forward so the helmet doesn't come in contact with the back of the trailer. I've also seen the Louis Garneau helmets, which look a little more rounded instead of having a slightly pointed end.
So, we are looking for suggestions for helmets or adjustments that people have made to successfully have their infant/toddler ride in a trailer.