Since you are nursing, I would say no. Not to mention you'd probably be engorged and in a bit of pain since you aren't nursing for a bit of the trip (unless you were planning to pump, which could be a PITA on a trip like that too
Having said that, I AM letting my MIL fly with my dd back to her house (we currently live in south florida, and are moving to the northeast in a couple of weeks) We have two cars and my husaband and I both have to drive. We tried to find someone else to drive so that I could fly up too but it didn't happen. DD *hates* long car trips. She's ok going 15 minutes to the store, but any longer than an hour and you are talking major meltdown. DD isn't nursing anymore, as I had to wean her at 13 months so that I could take medicine. I totally trust my MIL with her (she will cosleep, GD, pretty much whatever I ask of her) and I know she will be much better off getting the trip done in a matter of hours on a plane rather than a matter of days in a car. I just think it was the best situation for both of us.
I would probably go if I wasn't nursing AND I knew that the kids would be with someone that I trusted completely (i.e. close family member) but since you are still nursing, I just don't know how that would work out for you without weaning him (and he is a bit too young IMO... I wouldn't have weaned dd at 13 months except that I was going downhill fast without meds to treat an autoimmune disorder