I use the Harbor Freight item un-bolted. I don't even pull up the carpeting anymore. Just set the wheel chalk down and load the bike. I do use the tie downs in the front corner.
Have only had one issue when I didn't put enough tension on the tie downs in over 10k miles. One strap came unhooked and I found my Street Glide tilted to one side when I got home. Luckily the Harbor Freight item is very strong.....the bike was fine.
Lesson learned....make sure to have plenty of tension on the tie downs...