I highly recommend a book called
Road Racing for Serious Runners. It has excellent training plans for 5K, 10K, 15K, half, and full marathon distances. There are more advanced, and scientifically detailed books out there, but if you want to keep it simple, this book is great. I've used the half marathon plan myself and was very impressed by it.
EDIT: Oops! I'm sorry, I just re-read your OP. The book I linked to does not have the type of plans you're looking for. You say you're looking for a "primal friendly" plan that does not involve running more than 3 days of the week. The plans in the book I linked will encourage you to run more often than that (though of course, you could modify them to suit your needs).
I think your current plan of one sprint day, one tempo day, and one long run day should work fine. The long run day is obviously going to be the most important one in terms of preparing you for the event, and as such it should be prioritized and never skipped. If burnout is a concern then you might consider dropping some of the cross training or the Jillian Michaels video, especially as mileage on the long run gets higher.
You didn't mention though, are you just looking to run the half marathon for fun, or are you racing it for a specific time?