Not quite the same, but I went to Cambodia and Vietnam when I was pregnant, at the start of 2nd tri. my morning sickness had eased but I hadn't got to the energetic bit of 2nd tri yet. We would go out in the morning and do something, come back and chill in the air con of the hotel for awhile in the middle of the day (I often had a shower and a nanna nap) and then head out again in the late arvo. I can imagine having to do similar if I was going with kids.