So I heard about this thing called the internet, I typed in how to install rivnut without tool and this wonderful little video popped up!
With new hope I revisited my morning project, now conveniently after the sun had set, pieced together the small metric
bolt then nut, washer, end of an angle grinder spanner, then nutsert/rivnut. Installed rivnuts into the chassis and the most difficult part of this project was over.
I'm a little displeased with the ~95 degree angle at which the step tends to sit, seems like it should be horizontal, perfectly 90 degrees with the vertical mount brackets. Appearing sturdy enough to lift the right honourable Winston Churchill into his trusty Land Rover. Fail! No apparent adjustments either.
When I step on the step it flexes further downward, doesn't feel very assuring and the foremost hinges towards the front of the vehicle have some have some play in them, the rearmost hinges on the step have no play. Seems like there should be some bushings in the step hinge to make it more sturdy. The rubber bushing requires you to drill a hole through the sill panel right through a spot weld for one of the sill brackets. Not so sure about that. Will probably postpone fitting that.