^^^ Why not just back out of the space, and then put him in?

What with kids in (usually) blinged up civics who have to park diagonally across two spaces?

He's only two - couldn't stand there on his own whilst I backed it out and the wife wasn't with me to watch him....

I did consider sitting him in the seat, backing it out and then putting him in.... but that would have had the same net result anyway i.e. he thought he was going to sit in the seat with no car seat and then had a strop when got put in his proper seat.....