Transport back to Pamplona?

My wife and I are doing the first 12 days of the Camino starting in SJPP, and probably ending somewhere between Logroño and Burgos. We'd like to finish the last day's walking and then find transportation back to Pamplona the same day. The next morning, we'll take a train back to Madrid and fly out that same afternoon.

Unfortunately the train has to be from Pamplona - the trains from Logroño and Burgos are too late that day for us to make our flight, so we would have to stop walking a day earlier and stay a night in Madrid.

If all goes according to plan, the last day of walking will put us somewhere between Logroño and Burgos - maybe Santo Domingo de la Calzada. I found a web site for PLM Autocares (in Spanish), which seems to be a bus that goes that route at 18:25, and might work out well. Anyone familiar with transportation in this area?

BTW, the train would get us in to Madrid Atocha at 09:45 and our flight is at 13:00. Is that too close?

Thanks!
Russell
http://www.farofflands.com/camino/

UPDATE: I've decided the timing is too tight, and the cost of missing the return flight is too high (over $2000 each!), so we'll be spending the night before in Madrid now. Details in my post below. Thanks anyway.

Thanks everyone, for the helpful info.

I started thinking about the complications here, and the timing involved, and started getting more concerned about missing the flight. So I called American Airlines to see what the price difference would be if we had to re-book the flight for the next day. It wasn't pretty.

$200 change fee, plus the difference between what we originally paid back in January, and what a one-way (not round-trip) ticket would cost the next day. At the moment, we'd have to pay an additional TWO THOUSAND DOLLARS. Each.

So, uhhh.... nevermind. we'll be finishing a day early and staying the night before in Madrid.

Thanks anyway tho,
Russell