Your getting stuck in irons because you have more weight forward (with the extra people).

If you're sailing with a jib let it back fill on the new tack for a second or two before brining it to the new tack. This helps suck the bows around.

Once stuck in iron the only real way to get out is, like you said, reverse the rudders. Remember once you're stuck in irons you're moving backward so all you're steering is effectively reversed.

Tacking, like sailing in general, really is an art. However there are a few things that you have to keep in mind:
1. Pick you're spot, when the boat is moving, you're not in a gust and where you wont tack into a wave.
2. Go into the tack smoothly (not too hard on the tiller) and with speed.
3. Finish the tack a little heavier on the tiller (this will get the boat moving quicker out of the tack.
For you're problem the second point is the most important.

Hope it helps