Rear mount child seat on a Stromer?

[hebs]

Hi folks - has anyone with a Stromer used a rear child seat on their bike? Stromer's website seems to suggest this would be OK but the rack is only rated to 17kg. I'm wondering if anyone has installed an aftermarket rack and a child seat with it. (I'm thinking about getting a Stromer but would need to put a kid seat on the back for preschool drop off, and our 3 year old is 43 lbs). Thanks in advance!