One, the overall build quality of that thing doesn't look up to riding 2800 miles. Two, is that the original fork? Something about the rake/trail doesn't look right. Three, I don't think that bike was intended to be ridden at speeds that you can develop with it motorized, or descending with a load. Four, I can't begin to imagine how it s going to handle, without a stoker, but with the dead weight of a motor, and a load.
It sounds like you must be fairly handy, so with some work you may be able to McGiver that bike through an extended tour, but it wouldn't be my choice for setting out on one.
As Zona suggests, it would be a lot more practical to pull a bob trailer behind a single bike.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.