Happy to help.

I should have mentioned a slightly different option of rack seating is basically to install a cushion, some rails, and running board to keep the little legs from flopping around.

The rails are kind of hard to search online for because they get called a lot of different things. I found this one by Surly, and this other one by Yuba.

That couple I mentioned before have a set of these on the one bike they take two of their children on. I don’t think they have running boards on their bike, but I’ve seen other people use them and think they’re a good idea. Here’s a post I found from some guy that made his own for a few bucks.

Benefit of the rails over the specific child seat is the rails still help hold cargo for when you need it.

Keep in mind, this whole kid on a rack option will change your centre of gravity, and starting, stopping, and slow maneuvers in general will feel a bit different.

Hope it works out!