If choosing USB-HDD won't work, see your post Should I Be Concerned and Extra Cautious - Page 12 - Windows 10 Forums and try that, just don't worry about changing the bios settings. They have worked well for you so far. Just try the last 2 steps.
You have your Wife's Laptop right? You can post while it is installing and ask any questions that come up. One I know you will be asked is do you want to download updates. The Microsoft servers are so busy today from people trying to do the same thing you are doing, so select no. It is a gamble, but let's try it that way.
TA DA! It looks like it works. Back to my machine.
Oh ye of little faith!