Racktime rack for Stromer ST1

I have a Stromer ST1 with a Racktime rear rack (Part number is EN 14872 with a max load capacity of 10 kgs).

It works great for carrying my panniers when I am biking to work.

However, I am looking to install a rear child seat (like the Burley Dash RM) and it turns out that the current Racktime rack isn't compatible (too narrow and not enough of a weight limit).

I can get another rack, but the thing that confuses me is on my Stromer, the rack is actually screwed into the rear mud-guard. The rear light also attaches to the racktime rack, so I wonder if the racks were customized to the Stromers? Would the install work if I get another racktime rack or does it have to be a custom job?

Hopefully someone with a Stromer and a racktime rack can comment.

Thanks!

Avi
 
I should have simplified my question rather than rambling: is there a replacement Racktime rack which is wider and has a higher load rating that I can replace my current rack with?
 
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