It IS doable. Or I should say I've done it myself. Just be aware that it rains a lot. Also if it's afternoon and clear you'll really feel that hot sun. But as long as your bags roll and you're not weighed down too much you'll be fine. The road between the 2 terminals isn't so heavily trafficked. A lot of the way doesn't have usable sidewalk but I didn't feel it was too dangerous on the side of the street.

By the way, there is a free shuttle between terminals. As you exit the doors of terminal one its stop is 50 meters or so to the left.