Kid's with helmets in bike trailers
last week i picked up a bike trailer for my toddler (2 yr old). friday evening, we got him a helmet. my question is, pre-helmet, i have the straps set up so he doesn't slump over and he's stays upright as much as possible. now. once we begin wearing the helmet, i know it will push against the back of the trailer and push his head slightly forward. is there any kind of seat cushion that i can get to sit him on so it gives him enough distance between him and the back of the trailer so his head will stay up.
i searched around, and i've seen where people just cut a slit in the back out the trailer, but i'd rather keep that as a last resort. any other options?