I am so sorry about the disappointing results.  I'm hatching shipped  AC's right now.  I have out of 14 I set, 7 made it to lock down. Only 3 have hatched so far.  2 more pips, but that's it.   Day 21 started an hour ago, so I think they still have time.  Of 12 shipped silkies, 7 made it to lock down, 3 have hatched, 1 pip.  Of my own eggs I set, 10t, 7 made it to lock down, 5 have hatched, 2 pips.  So, shipping is rough.  
I agree, the heat has got to be horrible on shipping eggs.  I saw someone post earlier that they would use cold packs to ship eggs. I'm sorry your second was such a disaster,
I have a broody that every time she gets up to eat, someone else jumps in and lays an egg.  She had 12 eggs under her (she is a silkie) so my tenant that helps care for the chicks, thought she would be helpful and pull 6 out.  She didn't candle them.  She just chose 6.  They were outside in 110 degree weather for 30 minutes before I found out. I figure that is probably warmer than it was under the hen, but not long enough to kill them, so I dropped the 6 in to my running incubator.  I'll candle them at some point, but they could be anywhere from day 1 to day 14. 
I thought I was close to being done hatching for the summer.  I have about 6 eggs that are on day 16, and another 45 or so, that are on day 11.  Now I added these silkies, and a friend picked up a dozen BCM that she wants me to hatch.  So, I'll add hers, and will top off the rest of the bator with the last of my EE eggs that I think are fertile.   
THEN I will be done hatching for the summer.