Installed mine this morning. Thanks to all the posters before me that offered great tips. Mine went like this:
1. Removed the 13/16 existing bolt at top left using a 1/2 drive flex head ratchet. This flex head ratchet made it so much easier btw, thanks for the suggestion.
2. Pulled all existing wires up together and zip tied them out of the way.
3. Re-used the 13/16 original bolt in top left hole, and used two of the 7/8 bolts from baggie in other two holes. I did not use any of the nuts from baggie, as all three of my holes were threaded and welded on nuts already.
4. I enlisted my wife to hold the extended step for a second while I threaded one bolt in. Easy peasy.
5. Admired my handiwork.
I'm trying to get the feel of operating it with my foot, particularly when closing it as it really slams up. But I checked and it is not hitting anything at all, so it should be all good.