Just out of interest, do the roads really need to be closed for 12 hours? Assuming the race doesnt start til 7am, you could start to close them at 7.30am, (depending on the route some coiuld close later?) then start to close them as back markers went though? Allowing for a 2.20 swim, and 10 minutes in T1, you could probably open roads round T1 for a few hours inbetween last rider leaving and first riders home? Even the slowest rider will only be out for 8 hours or so (cut off for combined bike and swim is 10 hrs 30 mins) and half the course would presumably be clear long before that?
I've not studied the route but presumably after certain times some roads could be open after the last rider is through?
I realise that where there are feed stations being set up you would need to take extra precautions etc. and cordon off a safe area around them whilst they are being set up etc.
You would also need to police the roads more carefully, ensuring that they opened and closed at the right time (and had flexibility if riders should be particularly fast or slow) but you could turn this back on the villagers and say that they needed to police their own village in accordance with the times specified, or it would be closed solidly? That should see just how in favour they are of the race "in principle"!
Just showing willing!
Having said all that, whilst clearly I would prefer closed roads, did anyone doing the Outlaw really feel they were hindered by traffic? We knew when we were on a busy road and were sensible.