Hi Shawn,
I have a 5yr. old, and have been looking for a way to do this. I trial-fit the up-to-40lb. child seat sideways behind the pax. seat, but it was too wide. I now plan to make a similar to stock set-up, out of upholstered plywood. I hope it won't be for nothing, since my girl is a real "princess", and she just might nix it as too windy/noisy/messy hair!!
Will W14
1965 230SL 4spd
Victoria,BC