Have you considered maybe passing on this run and building back up to a half before tackling another marathon, post-surgery? If you're in pain while doing low-resistance training (or while walking!), that's not a good sign. It also sounds like you don't have enough time to recondition your body to a long race. Granted, since this will be your 10th marathon, I guess your legs will certainly recognize the distance, but my concern is how the rest of your body will handle the stress.

+1 to the above posts. I had a major abdominal laproscopic procedure in July 2009, and I was ready to begin running again four weeks post-surgery. Rather than take the risk of injuring something for the long haul, I aimed for a half-marathon four months later.

I trained conservatively for that and still ran a PR. From there, I trained for another marathon (and did an ultra during that training cycle just for fun). As noted, we're not always that good at listening to our bodies (or at least we're pretty good at creatively interpreting what our bodies say), so I'd strongly recommend taking a conservative approach to make sure you'll be able to run many, many marathons down the line.

Don