Here is what happened.
I called the MSF and they said the recommended position for the trike was in the rear due to the quick stop potential, visibility and width that did not allow the standard stagger. If in the middle a double distance to the next bike was recommended.
The day before the ride I saw the lady at the Mexican restaurant and asked her if she would ride the sweep position for us due to her better visibility. She said that would be fine and then I added that I did call the MSF and and gave her the findings as I stated. I then asked the most experienced rider to "Sheppard" her by riding in front of her and riding as a two bike team, never leaving her for any reason. He accepted and she was pleased to hear that because she did not wan to to get separated and lost while out of state.

We got back from our 1500 mile trip and all is well. She did ask that she not be put behind two riders that we ride with on occasion. Her reason, they are to slow.

Shame these two blokes would hold up an old lady on a trike.