Hi John
The trouble with any training program, especially for an ultra, is that it is very difficult to find a one-size-fits-all schedule. What you have looks good, and obviously your ironman background is showing through. I would be inclined to put divide up a bit more of your time to running in the build up, to peak around the 6-8 weeks out, allowing plenty of time for recovery.
As for back to back long runs, I'd only do this a couple of times around those peak mileage weeks. It's just a good way of getting some tough endurance training in without having to go out and run 70kms in one go(which would be counter productive given the recovery time needed, and increase risk of injury). So by doing two 30-40kms runs can simulate the endurance training without the intensity and impact of doing it in one hit.
I'm a big fan of training with a loaded pack, and do nearly all my sessions with my pack containing all my race kit. With 3l water in mine comes out around the 5-6kg mark. After a few runs though you don't notice it, and also get to find out any areas that rub and how to adjust the pack to give you a comfortable run.
All the best with the training
Andy
www.ultramarathonrunning.com.au