We also just purchased the same model steps from Lippert and discovered that there were several issues with installing them in our 2016 Classic.
Luckily we had worked in the past with a Southern California design firm which specializes in Airstream custom renovations:
https://innovsb.com/ They reworked the trailer's threshold and "tweaked" the hinged mounting plate of the Solid Steps.
We're quite happy with the results . . . the Lippert product is well built and Innovative Spaces was very creative in installing the steps.