I wouldn't bank on being able to get taxi's to and from the photo spots.
Both the morning and afternoon spots are a bit off the beaten track.
I was able to get a taxi from the airport to the morning spot when I was there back in May 2000 but the driver was seriously pissed at having to drop me off no more than a few miles into what I'm sure he hoped would be a big fare having waited in the rank at the airport for ages!
Even if you are able to get a taxi to one of the spots there is little chance (I'd say none realistically) of getting one from one of the spots back to either the airport or your digs. Believe me (and others) - you really do need a car...or at least a scooter or bicycle.
Thinking about it...there may be a chance of a bus to/from somewhere close to the morning spot as this is only a few hundred yards from a main road. No such luck in the afternoon though.
This page at Toni Marimons excellent PMI site has a map - spot 3 on the map is the morning spot, spot 1 the afternoon spot. The roads (shown in red) between spots 4 and 5 to the west of the airport are pretty much all motorway and very difficult to get around on foot in this area.
I hope Toni doesn't mind me posting this here. I used this map myself when I was there and it was a great help.
Life's dangerous. Get a f**king helmet!