I know that the new mode is still not "cleared" from bugs and etc, but it haves some problems . Level 1 has like ultra box drop rate and this makes it hard to get Tier 3 or even Tier 2 parts. Level 64 - Overpowered mobs , played like 5 times and still no boxes , and the map is very laggy (Probably because of the overused Scalpers) and its not from my computer . I still haven't played other than survival level 1 , 64 and 137 because i am level 134 but that's the problems i encounter while playing Survival mode.
the over-crowded with boxes thing is just a part of the challenge
try to find a friend who can get the boxes for you until you reach tier 3