[Girlene]

A good bet would be someone from the safe house saw them go down, ( on a motorcycle perhaps ? ) and went up to position himself if the convoy took that route going back.

Could be. It doesn't sound like they normally took Route Chestnut back to the base. If that is River Road next to the safe house, then it would make sense that occupants of the safe house would see the convoy going and coming.

[RedRover]

Can you handle pdf files? You may find this of interest. (You'll need to rotate the page view counterclockwise.)

The graphics couldn't be of worse quality, but if you enlarge them you can make out the text and possibily some of the landscape. Ultimately, I'd like to recreate what's here with images from Google Earth.